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2001 TMS Fall Extraction and Process Metallurgy Meeting:
Computational Modeling of Materials, Minerals,
and Metals What follows is the final technical program of the
2001 TMS Fall Extracting and Process Metallurgy Meeting:
Computational Modeling of Materials, Minerals, and Metals which was
scheduled for Setpember 23-26, 2001. Following the events of
September 11, 2001, the ongoing difficulties associated with U.S.
and international air travel, and the cancellation of nonessential
travel by the employers of many attendees and presenters, this
meeting has been postponed until further notice. This technical
program is being provided for archival purposes, and does not
necessarily represent the planned symposia of the rescheduled
conference.
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Monday AMOpening Plenary Session
KeynoteMulti-Physics Simulation of Metal Processing:Mark
Samonds
KeynoteComputing the Dynamic Interaction ofMagnetic Fields and
Turbulent ConductingFluids in Metals Processing: Koulis
Pericleous
10:30 AM Break
Track A - CFD Modelling - I10:45 AMSimulation of Turbulent Flow
and ParticleTransport in the Continuous Casting of Steel:Q. Yuan;
T. Shi; S. P. Vanka; B. G. Thomas
11:10 AMCFD Modeling of the Hydrodynamics ofFluidization in the
Sand Surrounding a LostFoam Casting Pattern:Nathanael
HarrisonHudson; Sushil Bhavnani; Ruel A. Overfelt
11:35 AMContinuum Modelling of Granular Flows usingPHYSICA, a
3-D Unstructured, Finite-VolumeModelling Framework: Nicholas
Christakis;Mayur K. Patel; Mark Cross; John Baxter;
HadiAbou-Chakra; Ugur Tüzün
12:00 PMMathematical Model of Inclusion Removalduring Steel
Degassing: Michel Cournil; FrédéricGruy; Pascal Gardin; Hubert
Saint-Raymond
12:25 PMApplication of Coupled Continuum-Mesoscopic
Computational Methods for theSimulation of Complex Fluids in
IndustrialProcesses: Greg Glinski; Chris J. Bailey;
KoulisPericleous
Track B - Heat & Mass Transfer - I10:45 AMHeat Load Control
of Blast Furnace Wall usingStatistical Optimization Techniques:
Tae-hwaChoi; Yong-hwan Chu; Chonghun Han
11:10 AMMathmatical Modeling and ExperimentalVerification of
Assimilation of ExothermicAdditions in Liquid Metals: Stavros
A.Argyropoulos; Henry H. Hu
11:35 AMA Model of the Cathode Dynamics in
ElectricField-Enhanced Smelting and Refining ofSteel: David Michael
Dussault; Adam Powell
12:00 PMA Mathematical Model for the Control ofMetallurgical
Properties of the Product Sinter:Ndabezinhle Manengi Dube; E. F.
Vegman
12:25 PMModelling the Magnetostriction of TexturedFerromagnetic
Materials with a CubicStructure: Ruben Decocker; Leo Kestens;
YvanHoubaert
Monday PM Plenary SessionKeynoteModelling and Process
Optimization forFunctionally Graded Materials: Dan Tortorelli
Track A - Optimization & NovelMethods
2:45 PMLattice Boltzmann Methods for MetallurgicalProcess
Simulation: Christian Redl
3:10 PMViscosity Estimation Model for an OscillatingCup
Viscometer: Deming Wang; R. A. Overfelt
3:35 PM Break
3:50 PMNumerical Optimization of MagnesiumReduction in a
Modified Pidgeon Process: AlfredYu; Henry Hu
4:15 PMDeterministic and Regression Models of NickelOxide
Reducing Roasting Process: V. M.Paretsky; A. V. Tarasov
4:40 PMIntegrating Computational Mechanics andNumerical
Optimization for the Design ofMaterial Properties in Electronic
Packages:Stoyan Stoyanov; C. Bailey; M. Cross
5:05 PMComputer-Aided Modeling and Control ofAutogenous Copper
Smelting Process: A. V.Tarasov; V. M. Paretsky
Track B - Melting & Solidification - I2:45 PMA Marker Chain
Front Tracking Method forModelling Meniscus Dynamics in the Al
IngotCasting Process: Fionn Iversen; Jon Arne Bakken;Stein Tore
Johansen
3:10 PMComputational Modeling of Heat Mass andSolute Transport
in Directional SolidificationProcesses: Mohammed El Ganaoui;
Patrick Bontoux
3:35 PM Break
3:50 PMComputational Modelling of Freeze Layers inSmelting
Processes: Andrew P. Campbell; KoulisA. Pericleous; Mark Cross
4:15 PMMathematical Modeling of Heat Transfer andMicroporosity
Formation in Die Cast A356Wheels: P. Vo; D. Maijer; S. L.
Cockcroft; M. A.Wells; C. Hermesmann
4:40 PMModelling Filters in Metal Casting Processes:Mark R.
Jolly; Jean-Christophe Gebelin
5:05 PMComputer Heat Transfer Model for DirectionallySolidified
Castings: Deming Wang; R. A. Overfelt
Tuesday AM Plenary SessionKeynotePhase Field Methods for
Modeling Microstruc-ture: James A. Warren
Track A - Structure9:45 AMMicroporosity Evolution and
InterdendriticFluid Flows during Solidification: Adrian S.Sabau;
Srinath Viswanathan
10:10 AMCellular Automata Computer Model ofPolycrystalline
Plastic Deformation: AlexanderV. Spuskanyuk; Yakiv E. Beygelzimer;
Victor M.Varyukhin
10:35 AM Break
10:50 AMSimulations of Microstructural Evolution:Martin E.
Glicksman; Kegang Wang; P. Crawford
11:15 AMAb Initio Calculations of Theoretical TensileStrength in
Metals and Intermetallics: MojmirSob; Ligen Wang; Martin Friak;
Vaclav Vitek
11:40 AMModeling of Interdendritic Strain and Interden-dritic
Cracking Phenomena during DendriticSolidification Processes:
Mostafa El-Bealy
Track B -Melting & Solidification - II
9:45 AMWax Injection in the Investment CastingIndustry:
Jean-Christophe Gebelin; AlexanderCendrowicz; Mark R. Jolly
10:10 AMMicro/Macro Modeling of Ingot CoolingProcesses for
Ni-Cu-S Alloys: ApostleMouchmov; Mark Cross; Koulis Pericleous
10:35 AM Break
10:50 AMComparison of Numerical Models of Solidifica-tion
Behavior in Direct Chill Casting withExperiments: Christopher J.
Vreeman; DavidSchloz; Matthew John M. Krane
11:15 AMTwo-Phase Predictive Finite-Element FlowModel for
Semi-Solid Slurries: Frédéric Pineau
11:40 AMCFD Simulation of Continuous Charging andMelting of
Small Metallic Particles in a MeltingReactor: Stefan Pirker; Oszkar
Biro; Philipp Gittler;Peter Mittag; Bernard Aigner
12:05 PMNumerical Simulation of Wax Pattern Dimen-sions in
Investment Casting: Adrian S. Sabau;Srinath Viswanathan
Monday AM Monday PM Tuesday AM
At-A-Glance Technical Program
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Tuesday PM Plenary SessionKeynoteComputational Modelling of
Metals ReductionProcesses: Phil Schwarz
Track A - CFD Modelling - II2:45 PMModelling of Raceway
Hysteresis: Govind S.Gupta; S. Sarkar; M. G. Basavaraj; P. D.
Patil
3:10 PMLifetime Prediction of Pneumatic ConveyorBends with the
Aid of Computational Models:Mayur K. Patel; Robert Hanson
3:35 PM Break
3:50 PMA Parametric Study of Oxy-Fuel Burners inSecondary
Aluminum Melting: MadhuHuggahalli; Neeraj Saxena; Ken Grieshaber;
JerryBernardski; David Stoffel
4:15 PMComputational Modelling of Vortex Formation inthe Lead
Refining Kettle: Suman Kumar; Chris Bailey;Mayur Patel; A. W.
Piper; M. Cowling; R. A. Forsdick
4:40 PMCFD Modeling of Solids Suspensions inStirred Tanks: Lanre
Oshinowo; André Bakker
5:05 PMWater Model and Numerical Study on theSpout Height in a
Gas Stirred Vessel: DiancaiGuo; G. A. Irons
Track B -Thermo-Mechanical Modelling - I
2:45 PMThick Yield Surface: An Approach to theProcessing of
Computer Experiments onPolycrystalline Deformation: Yan E.
Beygelzimer;Alexander V. Spuskanyuk; Victor Varyukhin
3:10 PMModel for Stress, Temperature and PhaseTransformation
Behaviour of Steels on Run-Out Table in Hot Strip Mill: Heung Nam
Han; JaeKon Lee; Hong Jun Kim; Young-Sool Jin
3:35 PM Break
3:50 PMThermo-Mechanical Coupling Finite ElementAnalysis of
Sheet Metal Extrusion Process:Zhanghua Chen; C. Y. Tang; T. C.
Lee
4:15 PMA Model for Calculating the Lankford Value inSheet
Steels: Sihai Jiao; C. Isaac Garcia; AnthonyJ. DeArdo
4:40 PMInterfacial Modelling of Hot Rolling: AProbabilistic
Approach: Sumitesh Das; Eric J.Palmiere; Ian C. Howard
5:05 PMComputational Experiment in the Mechanics ofMaterials:
Leon Mishnaevsky; Ulrich Weber; NilsLippmann; Siegfried
Schmauder
Wednesday AM Plenary SessionKeynoteMicro-Macro Modeling of
SolidificationProcesses and Phenomena: Vaughan Voller
Track A - Heat & Mass Transfer - II9:45 AMA Steady State
Electrothermic SimulationAnalysis of a Carbothermic Reduction
Reactorfor the Production of Aluminium: Dimitrios I.Gerogiorgis; B.
Erik Ydstie; Sridhar S. Seetharaman
10:10 AMThe Limitations of CFD Modelling for FurnaceAtmosphere
Troubleshooting: Paul F. Stratton;Neeraj Saxena; M. Huggahalli
10:35 AM Break
10:50 AMSimulation of Internal Oxidation: Henrik Larsson;Martin
Schwind; John Ågren
11:15 AMDynamic Model for a Vapor Recovery in Carbo-thermic
Aluminum Process: Vianey Garcia-Osorio; Tor Lindstad; B. Erik
Ydstie
11:40 AMComputer Simulation of the Structure-Energetical
Transformations at CombustionSynthesis in the Systems NiAl and
TiAl: MikhailD. Starostenkov; Gennadiy M. Poletayev; AlexandraS.
Starostenkova
12:05 PMInfluence of Surface Pressure and Slag Layer onBubble
Bursting in Degasser Systems: Julie Cranga;Pascal Gardin; Didier
Huin; Jacques Magnaudet
Track B -Melting & Solidification - III
9:45 AMComputational Studies of the Control ofConvection in
Diamagnetic Liquids duringSolidification with Magnetic Field
Gradient: C.B. Seybert; J. W. Evans
10:10 AMMethods for Approximating Discontinuous orRapidly
Changing Conductivity in NumericalCalculations: Vaughan Richard
Voller
10:35 AM Break
10:50 AMModelling of the De-Waxing of Investment CastShells:
Jean-Christophe Gebelin; Sam Jones; MarkR. Jolly
11:15 AMThe Swirling Effect in an Immersion Nozzle onthe Flow in
a Continuous Casting Mold:Shinichiro Yokoya; Sigeo Takagi; Manabu
Iguchi;Katsukiyo Marukawa; Shigeta Hara
11:40 AMComputational Modelling of Metals Extrusionand Forging
Processes: A. J. Williams; T. N.Croft; M. Cross
12:05 PMThe Role of Orifice Shape in the Detection ofInclusions
in Liquid Metals: Roderick I.L. Guthrie; Mei Li
Wednesday PM Plenary SessionKeynoteComputational Modeling of
Thermo-Mechanical Phenomena: Christopher Bailey
Thermo-Mechanical Modelling II2:45 PMMathematical Modeling of
Mean Flow Stressduring Hot Strip Rolling of Nb MicroalloyedSteels:
Ki Bong Kang; Sang Hyun Cho; John J.Jonas
3:10 PMModeling of Residual Stresses and MechanicalBehavior of
Glass-Infiltrated Spinel CeramicComposites: Anil Saigal; Edwin R.
Fuller; SaidJahanmir
3:35 PM Break
3:50 PMSimulation of Fatigue Stress Life (S-N)Diagrams for
Ti-6Al-4V Alloy by Application ofArtificial Neural Network: S.
McShane; SavkoMalinov; J. J. McKeown; Wei Sha
4:15 PMPrediction of Lateral and Normal Force-Displacement
Curves for Flip-Chip SolderJoints: Daniel Wheeler; Daniel Josell;
James A.Warren; William E. Wallace
4:40 PMSimulation of the Plastic Behavior duringMechanical
Testing of Galvanized Steel usingthe Finite Element Method: Adriana
Salas;Martha Patricia Guerrero Mata; Rafael Colás; RenéGarza
Tuesday PM Wednesday AM Wednesday PM
At-A-Glance Technical Program
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Technical Program Grid
Monday-September 24 Tuesday-September 25 Wednesday-September
26
AMPMAMPMAM PM
Track B -Heat &
Mass Transfer - I
Por
tofi
no/
Mar
seil
les
St.
Trop
ez Track A -CFD Modelling - I
Track A -Optimization &Novel Methods
Track B -Melting &
Solidification - I
Track B -Melting &
Solidification - II
Track B -Thermo-
MechanicalModelling - I
Track B -Melting &
Solidification - III
Track A -Structure
Track A -CFD Modelling -II
Track A -Heat &
Mass Transfer - II
Thermo-Mechanical
Modelling - II
St.
Trop
ez/M
onte
Car
lo
Monday AMOpening Plenary
Session
Monday PMPlenary Session
Tuesday AMPlenary Session
Tuesday PMPlenary Session
Wednesday AMPlenary Session
Wednesday PMPlenary Session
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2001 FALL EXTRACTION AND PROCESS METALLURGY
MEETING:COMPUTATIONAL MODELING OF
MATERIALS, MINERALS & METALS PROCESSING SYMPOSIUMSeptember
23–26, 2001San Diego, California
Monday AMOpening Plenary Session9:00 AM–10:30 AM
Monday AM Room: St. Tropez/Monte CarloSeptember 24, 2001
Location: Hilton San Diego Resort
Session Chairs: Mark Cross, The University of Greenwich, Centre
forNumerical Modelling & Process Analysis, Old Royal Naval
College, 30Park Row, Greenwich, London SE10 9LS UK; James W.
Evans,University of California, Dept. of Matls. Sci. & Min.
Eng., 585 EvansHall, Berkeley, CA 94720-1760 USA
KeynoteMulti-Physics Simulation of Metal Processing:
MarkSamonds1; 1UES Software, Inc., 175 Admiral Cochran
Dr.,Annapolis, MD 21401 USA Manufacturing processes which involve
liquid to solidand solid state transformations in metals encompass
a widevariety of physical phenomena. The past twenty years haveseen
a steady evolution in the complexity and scope ofnumerical models
of these processes, beginning with ther-mal analyses without phase
change. Recently, a few soft-ware packages have become available
which have truemulti-physics capabilities. This permits the
treatment ofthermal, fluids, stress, electromagnetic, chemical
reactionand microstructure development aspects altogether in afully
coupled simulation. This paper will consider variousaspects of
these types of models.
KeynoteComputing the Dynamic Interaction of Magnetic Fieldsand
Turbulent Conducting Fluids in Metals Processing:Koulis
Pericleous1; 1University of Greenwich, GreenwichMaritime Campus,
Queen Mary Ct., Rm. 361, Greenwich,London SE10 9LS UK Magnetic
fields have many actual applications in themetals processing
industry. Externally applied magneticfields give rise to
electromagnetic (Lorentz) forces formedby the cross product JxB,
between the induced current den-sity J and the magnetic field
density B. When the metal is inliquid form, the Lorentz force
generates motion in the fluidwhich in applications of practical
interest becomes turbu-lent. In modelling terms, the Lorentz force
appears as asource in the momentum equations. In addition, the
in-duced current generates heat (Joule heating) in the metal
that is in proportion to J2, with a corresponding souirceof heat
in the energy equation. Whether as heat or as aforce, these effects
represent action at a distance–a mostuseful attribute when dealing
with hot metal. The Lorentzforce is used to stir solidifying
alloys, pump liquid metal inconduits, dampen the flow in the
meniscus of a continu-ous caster, levitate metal drops, induce
artificial gravityconditions in suspensions or contain liquid
metal. Else-where, the Lorentz force may be a by-product of some
otheroperation, so leading to wave excitation in aluminium
elec-trolysis cells, or altering the shape of the weld pool in
arcwelding. Joule heating is most commonly used with ap-plied AC
fields, to melt metal in induction furnaces. Theauthor and his
colleagues have been involved in the mod-elling of most of these
processes in the past decade. Model-ling is not however
straightforward, since most of the ex-amples mentioned represent
genuine multi-physics chal-lenges. There is a strong coupling
between the flow fieldand electromagnetic field. The addition of a
dynamicallyvarying metal free surface and the moving solidus
frontmeans the flow, heat and electromagnetic fields need to
becomputed simultaneously. In situations involving
metalcontainment, the metal free surface position is governed bythe
interplay of gravity, Lorentz force, surface tension andfluid
inertia. Since all the interesting effects often happenin thin
boundary layers at the surface due to the skin effect,mesh
generation and mesh control during the computa-tion become non
trivial problems that need to be addressed.This paper presents a
review of numerical methods used tomodel droplet levitation,
semi-levitation melting and coldcrucible induction melting of
metals. The first method isbased on spectral collocation techniques
and the second isthe traditional FV approach. Steps taken to
validate thecomputations and typical transient results are also
given.
10:30 AM Break
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Track A - CFD Modelling - I
Monday AM Room: St. TropezSeptember 24, 2001 Location: Hilton
San Diego Resort
Session Chairs: Mark Samonds, UES Software, Inc., 175
AdmiralCochran Dr., Annapolis, MD 21401 USA; Mayur Patel,
University ofGreenwich, Ctr. of Numcl. Modlg. & Proc. Analy.,
London SE10 9LSUK
10:45 AMSimulation of Turbulent Flow and Particle Transport
inthe Continuous Casting of Steel: Q. Yuan1; T. Shi1; S. P.Vanka1;
B. G. Thomas1; 1University of Illinois at Urbana–Champaign, Dept.
of Mechl. & Indl. Eng., 1206 W. GreenSt., Urbana, IL 61801 USA
The quality of continuous cast steel is greatly affected byfluid
flow in the mold region, especially involving tran-sient phenomena.
Mathematical models are being appliedto investigate many different
aspects of these phenomena,but their accuracy must be validated
before they can beapplied with confidence. As part of a long-term
effort todevelop and apply comprehensive models of the continu-ous
casting process, this work evaluates the relative accu-racy of
models of three different fluid flow phenomena incontinuous casting
through comparison with measure-ments. Firstly, transient flow
simulations of velocities inthe mold region are compared with
digital particle imagevelocimetry (PIV) measurements in a single
phase watermodel. Large-eddy simulations (LES) are found to
reason-ably match the flow measurements, including transient
flowvariations, except at long time scales, which could not
bemodeled owing to the excessive computation costs. Thestandard K-e
model produced very good agreement withtime-averaged velocities for
relatively little computationtime, although it is inaccurate at
predicting the transientvariations. Secondly, particle trajectory
calculations arecompared with water model measurements to study
thedistribution and flotation removal of inclusion particles.The
LES model was able to match the measurements bothqualitatively and
quantitatively. Thirdly, steady, multiphaseflow computations are
compared with flow patterns ob-served in both a water model and an
operating steel casterwith argon gas injection. For the same
conditions, the wa-ter model and steel caster produced very
different flow be-havior. The computational model was able to match
themeasured flow patterns in both cases. This work suggeststhat
computational flow modeling has the potential tomatch real
processes as well or better than water models,especially when
complex related phenomena such as par-ticle motion and multiphase
flow are involved. Much workis still needed to further improve the
models and to applythem in parametric studies.
11:10 AMCFD Modeling of the Hydrodynamics of Fluidization inthe
Sand Surrounding a Lost Foam Casting Pattern:Nathanael Harrison
Hudson1; Sushil Bhavnani1; Ruel A.Overfelt1; 1Auburn University,
Dept. of Mechl. Eng., 213Ross Hall, Auburn University, AL 36849 USA
In the aerospace and automotive industries, shapes arisewhich
require casting. The problem with these cast parts isthe empiricism
and expense in developing an efficient cast-ing process. There has
been an interest in using the fluid-ized bed to allow sand to
better encapsulate the compli-cated surface geometry of a lost foam
pre-casting mold.Fluidization helps to eliminate the voids in the
sand andimproves the integrity of the casting. At issue is the
hydro-dynamics of the sand and air around the pre-casting mold.The
software PHOENICS, employing a two-fluid approach,is used to
simulate the flow of sand and air as interpen-etrating continua.
The kinetic theory of granular flow forthe sand phase is
incorporated into the re-compilablePHOENICS code. The results of
this study consist ofvoidage patterns and the velocity components
of the re-spective phases around the pre-casting submerged in a
two-dimensional fluidized bed. The model is benchmarkedagainst
experimental voidage patterns without a foam pre-casting and to
some trials with a pre-casting. The final testconsists of a series
of computer runs with an obstacle sub-merged in the bed at various
aspect ratios of length to width.
11:35 AMContinuum Modelling of Granular Flows using PHYSICA,a
3-D Unstructured, Finite-Volume Modelling Frame-work: Nicholas
Christakis1; Mayur K. Patel1; Mark Cross1;John Baxter2; Hadi
Abou-Chakra2; Ugur Tüzün2; 1Univer-sity of Greenwich, Ctr. of
Numcl. Modlg. & Proc. Analy.,Sch. of Compg. & Mathl. Scis.,
30 Park Row, London SE109LS UK; 2University of Surrey, Dept. of
Cheml. & Proc.Eng., Guildford, GU2 5XH Surrey, UK In recent
years significant effort has been put in usingContinuum Mechanics
for the description of granularflows. Although these models are
partially successful incapturing some flow characteristics, they
lack essentialinformation on material properties, which are needed
toaccount for the interactions between different particles.Thus,
they are incomplete and can not be used to describeprocesses such
as hopper filling/emptying and pneumaticconveying, where
particle-particle interactions can lead tophenomena such as
segregation, degradation and agglom-eration. In this paper, a 3-D
unstructured Finite-Volumeframework is presented, which employs
interface trackingtechniques (VOF/SEA algorithms) to determine the
mate-rial-air interface. Separate routines are employed to per-form
the tracking of the individual material components ofthe granular
mixture in the bulk. Various transport pro-cesses, arising from the
micro-mechanical properties of thedifferent particle species in the
granular mixture, can beobtained through kinetic theory. The
transport coefficient(s)of each of the individual species can be
determined andanalysed in a micro-mechanical framework and the
trans-port process parametrised in the form of constitutive
model.These models provide the continuum theory with informa-tion
on the micro-mechanics. This work describes in detailthe numerical
schemes employed in the Continuum Me-chanics framework and the
micro-mechanical
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parametrisations that are implemented in the transportequations.
Model predictions for different flow conditionsand comparisons with
experimental data are presented andconclusions are drawn on the
model capability to realisti-cally predict and quantify the main
characteristics of granu-lar flows.
12:00 PMMathematical Model of Inclusion Removal during
SteelDegassing: Michel Cournil1; Frédéric Gruy1; PascalGardin2;
Hubert Saint-Raymond3; 1Ecole des Mines deSaint-Etienne, SPIN Div.,
158 Cours Fauriel, Saint-Etienne,Cedex 2 42023 France; 2IRSID,
Themef, Voie Romaine, BP30320, Maizières-lès-Metz, Cedex 57283
France; 3IRSID,PCMO, Voie Romaine, BP 30320, Maizières-lès-Metz,
Cedex57283 France The control of inclusion elimination is getting
more andmore important to obtain clean steel. But having a
predic-tive tool is still a challenge, because the number of
phasesis important in steelmaking industry: liquid steel, slag
layer,bubbles and inclusions (with a large range of compositionand
rheology). The paper presents the methodology whichis developed at
IRSID to predict oxygen content evolutionduring RH degassing. The
main mechanisms which haveto be considered are: -inclusion growth
by turbulent aggre-gation of elementary inclusions (keeping in mind
that liq-uid steel is a non-wetting medium for inclusions); the
diffi-culty is to express collision efficiency for alumina
particles,-inclusion removal by flotation; the difficulty for
aluminaclusters stems from the complex morphology of
particle;fortunately, the use of fractal concept makes it possible
tocope with this problem. The proposed paper describes thegeneral
modelling of inclusion removal taking into accountthe previous
mechanisms. Hydrodynamic parameters areobtained by means of Fluent
CFD package and a specificcoding is developed for cluster growth.
Influence of differ-ent parameters (fractal dimension, argon flow
rate) on time-dependant inclusion size distribution is given.
12:25 PMApplication of Coupled Continuum-Mesoscopic
Compu-tational Methods for the Simulation of Complex Fluids
inIndustrial Processes: Greg Glinski1; Chris J. Bailey1;
KoulisPericleous1; 1University of Greenwich, 30 Park Row,
Green-wich SE10 9LS UK Recent advances in new computational
modelling tech-niques such as Lattice-Boltzmann and Dissipative
Particlemethods offer the prospect of simulating complex fluidssuch
as colloidal and dense suspensions in industrial pro-cesses. These
methods provide a means to overcome chal-lenges that arise in
modelling such fluids due to the dis-parate temporal scales
present. These methods are termedmesoscopic methods as they lie
between computationalintense molecular dynamics and traditional
macroscopicCFD methods. This paper will discuss the use of the
meth-ods to simulate the movement and subsequent processingof
solder paste material in electronic component manufac-ture. Results
will be presented that show how these meth-ods are coupled within a
macroscopic CFD code to providedetailed predictions of solder paste
deposition onto aprinted circuit board. Comparisons between the
model re-sults and experimental data will also be presented.
Track B - Heat & Mass Transfer - I
Monday AM Room: Portofino/MarseillesSeptember 24, 2001 Location:
Hilton San Diego Resort
Session Chairs: Koulis Pericleous, University of Greenwich,
Green-wich Maritime Campus, Greenwich, London SE10 9LS UK; Stavros
A.Argyropoulos, University of Toronto, Dept. of Metall. &
Matls. Sci., 184College St., Toronto, Ontario M5S 3E4 Canada
10:45 AMHeat Load Control of Blast Furnace Wall using
StatisticalOptimization Techniques: Tae-hwa Choi1; Yong-hwanChu2;
Chonghun Han2; 1Pohang Iron and SteelCompany(POSCO), Techl. Rsrch.
Labs./Iron & Steel Mak-ing Rsrch. Grp., 1 Goedong-dong, Nam-gu,
Pohang-shi,Gyungbuk 790-785 Korea; 2Pohang University of Scienceand
Technology, Dept. of Chem. Eng., 31 san Houja-dong,Nam-gu,
Pohang-shi, Gyungbuk 790-300 Korea In the blast furnace, various
complex phenomena takeplace including mass transfers, heat
transfers, a lot of reac-tions and phase equilibriums, but systems
of these phe-nomena are not found out clearly even until now.
Conse-quently, it is very difficult to make fundamental models
onthese systems, which results in the operation based on
theheuristics of industrial operators by changing
operatingcondition little by little due to ignorance of the
optimumpoint. However, since this method is not systematic,
wepropose statistical optimization technique based on analy-sis of
historical data and empirical model building. In thisapproach, we
first find the variables which must be opti-mized and the
manipulated variables to adjust those re-sponse variables. Next, we
collect the necessary data forthese variables after preprocessing
such as removal of noiseand outlier. Finally, we construct
empirical models describ-ing the patterns of response variables in
terms of manipu-lated variables by PLS regression method, and then
thesemodels are used as objective functions for entire
optimiza-tion problem. By using appropriate optimization
algorithm,this multi-objective optimization problem is solved,
whichgives us the compromising optimum operating
conditionconsidering all response variables from the past
operatingconditions.
11:10 AMMathmatical Modeling and Experimental Verification
ofAssimilation of Exothermic Additions in Liquid Metals:Stavros A.
Argyropoulos1; Henry H. Hu2; 1University ofToronto, Dept. of
Metall. & Matls. Sci., 184 College St.,Toronto, Ontario M5S 3E4
Canada; 2University of Windsor,Dept. of Mech., Automot. &
Matls. Eng., 401 Sunset Ave.,Windsor, Ontario N9B 3P4 Canada The
assimilation of exothermic additions in liquid met-als exhibit an
array of unique coupled heat, mass and mo-mentum transport
phenomena. The phenomena are fur-ther complicated with the presence
of a moving boundary.In this paper a mathematical model will be
described whichsolves these coupled complex phenomena. The
SIMPLERalgorithm was employed to solve numerically the perti-
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nent partial differential equations. The computational re-sults
indicated that the exothermic heat of mixing leads toa rapid
increase of temperature around the moving bound-ary, which produced
an enhanced convective flow in theliquid phase. The intensification
of fluid flow around themoving boundary resulted in an acceleration
of the melt-ing process. An extensive verification of the
mathematicalmodel was carried out and will be described in the
paper.First, in a low temperature physical model consisting of
iceimmersion in different sulfuric acid solutions. In this
physi-cal model, both temperature and velocity measurementswere
carried out. The model results were compared withexperimental
measurements and they were found to be ingood agreement. Second, in
a high temperature work in-volving assimilation of silicon in high
carbon liquid iron.The model was also applied to predict fluid
flow, heat andmass transfer for this high temperature experiments
and areasonable agreement was obtained. In addition new
di-mensionless heat transfer correlations that quantify
thesecomplex phenomena will be presented.
11:35 AMA Model of the Cathode Dynamics in Electric
Field-En-hanced Smelting and Refining of Steel: David
MichaelDussault1; Adam Powell1; 1Massachusetts Institute of
Tech-nology, Matls. Sci. & Eng., 77 Massachusetts Ave., Rm.
4-117, Cambridge, MA 02139 USA A mathematical model of coupled
diffusion, electrochemi-cal reactions and fluid dynamics at the
cathode in electricfield-enhanced smelting and refining of steel is
developedusing the Navier-Stokes equations and the phase
fieldmethod. Experimental evidence indicates that the reactionrate
is limited by ferrous ion transport to the cathode, re-sulting in a
Mullins-Sekerka instability at the slag-metalinterface and the
growth of liquid iron fingers into the liq-uid slag. The
differential equations are discretized usingfinite differencing
with a uniform mesh, and the resultingsystem of nonlinear equations
is solved using a multidi-mensional Newton-Krylov method. Presented
are the for-mulation and two dimensional results, and issues
expectedto arise on extension to three dimensions are
discussed.
12:00 PMA Mathematical Model for the Control of
MetallurgicalProperties of the Product Sinter: Ndabezinhle
ManengiDube1; E. F. Vegman2; 1University of Zimbabwe, Fac. of
Eng.,Dept. of Metall. Eng., PO Box MP167, Mount Pleasant,Harare,
Zimbabwe; 2Institute of Steel and Alloys, Moscow,Russia In the
conventional practice of sintering, the quality ofthe product
sinter down the cross-section of the bed is quitevariable,with the
top layer consisting of weak sinter andthe bottom layer, strong
over-fused sinter of poor reducibil-ity. This points to a variable
distribution of the heat bal-ance in the sintering process down the
sinter bed. Thiscauses losses in the productivity of the sinter
machine andthe blast furnace. The experienced phenomenon caused
byvarying input of regenerated heat requires a zonal approachto the
study of the sintering process with the aim of pro-ducing a uniform
quality of the sinter cake. The currentwork includes a mathematical
model that would make pos-sible optimization of multiple-layer
sintering and segrega-tion technologies. It is based on a zonal
heat balance. This
calculation method presents the following prospects: 1.
Theminimum theoretically possible coke fines consumptionduring the
sintering of any type of iron ore fines can beestablished. The
optimum difference between the coke finesrates in the top and
bottom layers during multiple-layersintering should be easily
determined with the aid of thismodel. 2. On the basis of this model
an automatic controlsystem for the coke rates in the top and bottom
layers dur-ing two-layer sintering is possible. 3. The model can
beused to control the quality (chemical, physical and
metal-lurgical) of the sinter in any point down the sinter bedsince
the data input includes basicity, combustion zonetemperature, and
FeO content in the product sinter.
12:25 PMModelling the Magnetostriction of Textured
Ferromag-netic Materials with a Cubic Structure: Ruben
Decocker1;Leo Kestens1; Yvan Houbaert1; 1University Ghent,
Metall.& Matl. Sci., Technologie-park 9, Ghent, East-Flanders
9052Belgium A magneto-elastic model is presented to calculate the
ori-entation dependence of the magnetostrictive strain, ob-served
at saturated magnetization in ferromagnetic mate-rials with a cubic
crystal structure and an arbitrary crystal-lographic texture. The
formula of Becker and Döring is usedto express the anisotropy of
magnetostriction for a singlecrystal. In order to simulate the
macroscopic average mag-netostriction of a polycrystalline
aggregate (with an arbi-trary texture) the Reuss assumption of the
elasticity theorywas applied. According to this assumption the
variousorientations of the polycrystal can deform without
con-straints, producing local strain incompatibilities in
themicrostructure but observing a total stress equilibrium.
Themacroscopic strain is calculated as the weighted averageof the
individual strains of all orientations composing thepolycrystal.
The weight factors are determined by the vol-ume fractions of the
corresponding orientations of the giventexture, which can be
measured by standard X-ray diffrac-tion techniques. The model is
applied to simulate the varia-tion of magnetostriction (at
saturation) with respect to therolling direction for a standard
grade of non-oriented elec-trical steel. A brief comparison with
experimental data al-lows validating the basic model
assumptions.
Monday PM Plenary Session2:00 PM–2:45 PM
Monday PM Room: St. Tropez/Monte CarloSeptember 24, 2001
Location: Hilton San Diego Resort
Session Chair: Vaughan Voller, University of Minnesota, Saint
AnthonyFalls Lab., Minneapolis, MN 55414-2196 USA
KeynoteModelling and Process Optimization for FunctionallyGraded
Materials: Dan Tortorelli1; 1University of Illinois–Urbana, Dept.
of Mechl. & Indl. Eng., 350 MEB, MC 244,1206 W. Green, Urbana,
IL 61801 USA We optimize continuous quench process parameters
toproduce functionally graded aluminum alloy extrudates.
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To perform this task, an optimization problem is definedand
solved using a standard nonlinear programming al-gorithm.
Ingredients of this algorithm include 1) the pro-cess parameters to
be optimized, 2) a cost function: theweighted average of the
precipitate number density distri-bution, 3) constraint functions
to limit the temperature gra-dient (and hence distortion and
residual stress) and exittemperature, and 4) their sensitivities
with respect to theprocess parameters. The cost and constraint
functions aredependent on the temperature and precipitate size
whichare obtained by balancing energy to determine the tempera-ture
distribution and by using a reaction-rate theory to de-termine the
precipitate particle sizes and their distribu-tions. Both the
temperature and the precipitate models aresolved via the
discontinuous Galerkin finite element method.The energy balance
incorporates nonlinear boundary con-ditions and material
properties. The temperature field isthen used in the reaction rate
model which has as many as105o of-freedom per finite element node.
After computingthe temperature and precipitate size distributions
we mustcompute their sensitivities. This seemingly intractable
com-putational task is resolved thanks to the discontinuousGalerkin
finite element formulation and the direct differen-tiation
sensitivity method. A three-dimension example isprovided to
demonstrate the algorithm.
Track A - Optimization & NovelMethods
Monday PM Room: St. TropezSeptember 24, 2001 Location: Hilton
San Diego Resort
Session Chair: Dan Tortorelli, University of Illinois–Urbana,
Dept. ofMechl. & Indl. Eng., Urbana, IL 61801 USA
2:45 PMLattice Boltzmann Methods for Metallurgical
ProcessSimulation: Christian Redl1; 1Mining University
Leoben,CD-Lab. Appl. Comptnl. Thermofluid-dyn., Franz-Josef-Strasse
18, Leoben 8700 Austria The Lattice Boltzmann Method (LBM) solves
fluid dy-namics problems based on a discrete mesoscopic approach.It
is based on the Lattice Boltzmann equation which is aspecial
discretisation of the continuous Boltzmann equa-tion. Its principle
advantage is that it can handle complexphysical phenomena (like
interaction between differentcomponents and surface effects),
complicated boundary andinitial conditions very well, free from
many gridding andstability constraints that plague conventional
numericalmethods used for fluid flow simulations. The LBM
algo-rithm has a simple structure and acts locally, which
isfavourable for parallel computing. Complex structures likeporous
media can be resolved directly. Its potential for met-allurgical
process simulations is demonstrated in thepresent study which is
concerned with the simulation ofthe flow in a copper winning
electrolysis cell. The electro-lyte is modelled as the carrier
fluid and the oxygen is con-sidered via a so called active scalar
equation. The model-ling of buoancy, momentum exchange and the free
surface
requires special effort. The results of the simulation
arevalidated against experimental data obtained by
Laser-Dop-pler-Anemometry. Despite the simplifications made,
goodagreement was found.
3:10 PMViscosity Estimation Model for an Oscillating Cup
Vis-cometer: Deming Wang1; R. A. Overfelt1; 1Auburn Univer-sity,
Dept. of Mechl. Eng., 201 Ross Hall, Auburn Univer-sity, AL 36849
USA Viscosity measurements of molten alloys become moreand more
important in modern metallurgy engineering.Lack of the viscosity
data of many new alloys hampersmany CAD computer codes to apply in
casting manufac-tures. The oscillating cup viscometer has become a
domi-nant technique to measure the viscosities of high tempera-ture
molten metals. Unfortunately, the viscosity estimationmodel from
the observed logarithmic decrement and pe-riod of the oscillation
is very complicated. There are stilllarge discrepancies of
viscosity estimation values betweenusing different measurement
facilities or using differentviscosity estimation models for a same
molten metal. Thepurpose of the paper is to evaluate the accuracy
of an oscil-lating cup viscometer in Auburn University. Two
wellknown viscosity estimation models, Roscoe’s and
Torklep’sequations, are discussed and compared viscosity for
dif-ferent alloys. The theoretical literature for the fluid
flowinside an oscillating cup is reviewed and a more
accurateworking equation for Auburn oscillating cup viscometer
isdeveloped. Some design parameters of the oscillating
cupviscometer which also directly affect the accuracy of vis-cosity
estimation by using the working equation are dis-cussed. In
addition, applications and experimental mea-suring data are
presented in the paper for several differentcommercial alloys, such
as aluminum alloys: A319, A356and A201, nickel-base super alloys:
In713 and In718, andcasting irons, C40 Gray Iron and Ductile
Iron.
3:35 PM Break
3:50 PMNumerical Optimization of Magnesium Reduction in
aModified Pidgeon Process: Alfred Yu1; Henry Hu2;1Nanjing Welbow
North America Office, 601-969 Felix Ave.,Windsor, Ontario N9C 4C7
Canada; 2University of Windsor,Mechl. & Matl., 401 Sunset,
Windsor, Ontario N9B 3P4Canada A numerical model of heat and mass
transfer in the retortwas set up to simulate and optimize the
reduction phe-nomena in the process of Pidgeon magnesium
reduction.The simulations were run to determine the effect of
varyingprocessing parameters on the magnesium reduction time.The
model predicted the temperature distributions, the heat-ing curves,
the recovery ratio of magnesium, and the totalprocess time. The
predictions were used to optimize themagnesium reduction process,
the dimensions of retort, theshapes of materials, and reaction
cycle. Demo operationshows that, with application of the
optimizations, signifi-cantly production capacity increases in the
same furnace,reduction period decreases, energy consumption
decreases.
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4:15 PMDeterministic and Regression Models of Nickel
OxideReducing Roasting Process: V. M. Paretsky1; A. V.
Tarasov1;1State Research Center of Russian Federation, State
Rsrch.Inst. of Non-ferrous Metals “Gintsvetmet”, 13, Acad.Korolyov
St., 129515 Moscow, Russia A mathematical model of the
low-temperature (soft) nickeloxide reduction (SNOR) in a tubular
kiln has been devel-oped including an equation describing changes
in the nickeloxide content of the solid material along the length
of thekiln; an equation describing the changes in the content
ofreagents ensuring nickel reduction (i.e., hydrogen and car-bon
monoxide) in the gas phase along the kiln length; aswell as the
temperature along the kiln length. The kineticrelationships used
for the development of the model hadbeen determined based on
experiments conducted speciallyfor this purpose. Model
investigations were conducted todetermine the distribution of such
parameters along thelength of the kiln as the contents of metals
oxides in thesolids, partial pressure of hydrogen and carbon
monoxide,variations of the temperature depending on the SNOR
pro-cess conditions, including the kiln rotation speed. Basedon the
data obtained, a simplified regression model of thereducing
roasting process was developed.
4:40 PMIntegrating Computational Mechanics and
NumericalOptimization for the Design of Material Properties in
Elec-tronic Packages: Stoyan Stoyanov1; C. Bailey1; M.
Cross1;1University of Greenwich, Sch. of Compg. & Mathl. Sci.,
30Park Row, Greenwich, London SE10 9LS UK Silicon components
containing transistor circuitry are atthe heart of electronic
products such as computers, mobilephones, etc. These components are
connected to printedcircuit boards (PCB’s) using solder material
that acts as theconductor for both electricity and heat. During the
lifetimeof a product it will undergo many thermal cycles where
thechip becomes hot during product operation and then coolswhen the
product is switched off. At the product designstage engineers
undertake thermo-mechanical simulationsto predict the thermal
stress in the solder joints due to thisthermal cycle and to ensure
that the stress magnitude willnot result in early fatigue-type
failure. The design engineer’saim is to identify component
parameters which ensure thatthe solder will survive beyond a
certain number of thermalcycles. The aim of integrating
computational mechanicsand optimization tools together is to speed
up dramati-cally the design process. From viewpoint of a design
engi-neer in the electronics manufacturing sector, these toolscan
be used to quickly estimate key design parameters (i.e.material
properties, product dimensions, etc.) that will guar-antee the
required product performance. In this paper amodeling approach
coupling computational mechanicstechniques with numerical
optimization is presented anddemonstrated. The integrated modeling
framework is ob-tained by coupling the multi-physics
framework–PHYSICA–with the design optimisation
tool–VisualDOC.Thermo-mechanical simulations are presented that
predictthe creep strains in solder material. Different
numericaloptimization procedures: Direct and Response Surfacebased
optimization plus Design of Experiments, are testedas a part of
this modeling framework.
5:05 PMComputer-Aided Modeling and Control of AutogenousCopper
Smelting Process: A. V. Tarasov1; V. M. Paretsky1;1State Research
Center of Russian Federation, State Rsrch.Inst. of Non-ferrous
Metals “Gintsvetmet”, 13, Acad.Korolyov St., 129515 Moscow, Russia
Based on theoretical and experimental studies into thespecific
features of the mechanism, kinetics, aerodynamicsand heat transfer
parameters of the flame-type oxidation ofmetal sulfides in a stream
of technical-grade oxygen, a three-dimensional deterministic
mathematical model of an oxy-gen-flame smelting furnace has been
developed on the ba-sis of the zonal method for computation of heat
exchange.The model is presented in the form of equations taking
intoconsideration the radiation component of the selective
ra-diation, the convection component of mass transfer betweenthe
space and surface zones, heating of charge particlesdue to heat
conductivity, accretions formation on a multi-layer refractory
lining with inserted cooling elements. Theadaptation of the model
for a full-scale furnace has demon-strated the possibility for its
use for computation of mainsmelting process parameters. Multifactor
model investiga-tions were conducted and the results obtained were
ap-plied using statistical methods for development of a sim-plified
computational regression model describing the in-terrelation of the
main output parameters: temperatures offlame, lining, slag and
off-gas; heat fluxes to the lining;thickness of accretions; heat
removed by cooling elements;copper content of matte. On the basis
of this model, a blockdiagram of the algorithm was developed for
control of thethermal conditions of the furnace, as well as the
controlalgorithm itself.
Track B - Melting & Solidification - I
Monday PM Room: Portofino/MarseillesSeptember 24, 2001 Location:
Hilton San Diego Resort
Session Chairs: Vaughan Voller, University of Minnesota,
SaintAnthony Falls Lab., Minneapolis, MN 55414-2196 USA; Matt
Krane,Purdue University, Dept. of Matls. Eng., West Lafayette, IN
47907 USA
2:45 PMA Marker Chain Front Tracking Method for
ModellingMeniscus Dynamics in the Al Ingot Casting Process:
FionnIversen1; Jon Arne Bakken1; Stein Tore Johansen1; 1Norwe-gian
Institute of Science and Technology (NTNU), Matls.Tech. &
Electrochem., A. Getz vei 2B, Trondheim N-7491Norway In
conventional direct chill (DC) hot-top casting of alu-minium
extrusion ingot using ‘gas-slip’, poor surface qual-ity of the cast
ingot may appear. It is believed that thesedefects are related to
instabilities such as periodic oscilla-tions or folding of the
meniscus (the interface between liq-uid metal and gas in the
mould). The object of this work isto develop a stable and reliable
model for simulation of themeniscus dynamics. A new 2D cylinder
symmetric fronttracking model has been developed for the meniscus
propa-gation, and is implemented in a general Navier Stokes
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vii
solver. The model is based on a finite volume cubic splinemarker
chain technique. The advantages of the model is itsapplicability to
cases with large density ratios and its abil-ity to calculate
independent velocity fields for phases onseparate sides of an
interface, thereby making it possible tomodel the dynamics of thin
films with a thickness scalesmaller than the typical grid size.
Effects of surface tensionand wetting are also easily applied in
the marker chainmodel. The model is applied to the DC casting
process.Results are compared with data from plant test runs
andsuggestions are made on how to improve the casting pro-cess.
3:10 PMComputational Modeling of Heat Mass and Solute Trans-port
in Directional Solidification Processes: MohammedEl Ganaoui1;
Patrick Bontoux2; 1Université de Limoges,Phys./Numcl. Mod., 123
Albert Thomas, Limoges 87000France; 2CNRS, Numcl. Mod., IRPHE,
Marseille, 13451France During directional solidification,
absorption or rejectionof latent heat or solute by the
solidification front induceconvective flows in the liquid phase.
These convectivemotions affect heat and mass transfer in the
vicinity of thesolidification interface and is subject to many
studies. Inthis work a numerical approach is presented. To
avoidremeshing needed by front tracking methods a time-depen-dent
homogeneous formulation is considered to verify im-plicitly thermal
and solutal Stefan conditions at the inter-face. The numerical
solution is based on finite volume ap-proximation. The previous
work show that the presentmethod describe accurately the
hydrodynamic transitionand the interaction with the solid liquid
interface in thecase of pure material. This study focuses on the
occurrenceof solutal convection in gradient freezing applications.
Ina first step only the fluid phase is investigated and theresults
are validated with respect to spectral ones. In a sec-ond step the
full solid/liquid model is investigated. A lin-ear approximation of
the equilibrium phase diagram isconsidered for establishing
relations between mass frac-tion and temperature fields to close
the set of conservationequations. The present work shows that the
method is ableto describe with accuracy close to spectral one
complexphenomena occurring in reduced configuration to fluidphase.
The global model with solid phase account correctlythe interface
displacement and its interaction with solutalfield.
3:35 PM Break
3:50 PMComputational Modelling of Freeze Layers in
SmeltingProcesses: Andrew P. Campbell1; Koulis A. Pericleous1;Mark
Cross1; 1University of Greenwich, Ctr. for Numl.Modlg. & Proc.
Analy., 30 Park Row, Greenwich, LondonSE10 9LS UK The use of
computational modelling in examining pro-cess engineering issues is
very powerful. It has been usedin the development of the HIsmelt®
process from its con-cept. It is desirable to further water-cool
the HIsmelt® ves-sel to reduce downtime for replacing refractory.
Water-cooled elements close to a metal bath run the risk of
failure.This generally occurs when a process perturbation causesthe
freeze and refractory layers to come away from the wa-
ter-cooled element, which is then exposed to liquid metal.The
element fails as they are unable to remove all the heat.Modelling
of the water-cooled element involves modellingthe heat transfer,
fluid flow, stress and solidification for alocalised section of the
reaction vessel. The complex inter-action between the liquid slag
and the refractory applied tothe outside of the water-cooled
element is also being exam-ined to model the wear of this layer.
The model is beingconstructed in Physica, a CFD code developed at
the Uni-versity of Greenwich. Modelling of this system has
com-menced with modelling solidification test cases. These
testcases have been used to validate the CFD code’s capabilityto
model the solidification in this system. A model to trackthe
penetration of slag into refractory has also been devel-oped and
tested.
4:15 PMMathematical Modeling of Heat Transfer andMicroporosity
Formation in Die Cast A356 Wheels: P. Vo1;D. Maijer1; S. L.
Cockcroft1; M. A. Wells1; C. Hermesmann2;1University of British
Columbia, Dept. of Metals & Matls.Eng., Vancouver, British
Columbia V6T 1Z4, Canada; 2Ca-nadian Autoparts Toyota, Inc., 7233
Progress Way, Delta,British Columbia V4G 1E7, Canada Die cast
aluminum wheels are one of the most difficultautomotive castings to
produce because of stringent castsurface and internal quality
requirements. A mathematicalmodel has been developed to predict
heat transport andporosity formation in die cast A356 wheels as
part of acollaborative research agreement between researchers atthe
University of British Columbia and Canadian AutoParts Toyota
Incorporated. The heat transfer model, em-ploying the commercial
finite element code ABAQUS, is athree-dimensional, 30° slice of the
wheel and die that de-scribes forced air cooling, natural
convection of the die tothe surrounding environment, and
interfacial heat trans-port between the wheel and die sections.
Extensive tem-perature measurements in the die and in the wheel
takenover several cycles in the casting process were used to
finetune and validate the model. Preliminary work on predict-ing
porosity formation focused on using the Niyama pa-rameter as a
measure of the probability of porosity. Thelatest version of the
model incorporates a new more funda-mentally based porosity
criterion, which takes into accountthe effect of hydrogen and
inclusion content. The develop-ment of this model together with
some early results will bepresented.
4:40 PMModelling Filters in Metal Casting Processes: Mark
R.Jolly1; Jean-Christophe Gebelin1; 1The University of Bir-mingham,
IRC in Matls., Edgbaston, Birmingham, W. Mid-lands B15 2TT UK A
number of different types of so-called filters are usedon the metal
casting industries to impart some cleaningeffect and flow control
on the liquid metal as it passesthrough them. The filters range
from simple planar meshesthrough extruded channels to reticulated
foam structures.It is most common that software packages used in
the in-dustry model the filters by a simple pressure drop
associ-ated with some area fraction and permeability
parameters.Recent experimental work at the IRC in Birmingham
hasshown that filters of the same type can behave very differ-
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viii
ently depending upon the casting process in which theyare
employed. Modelling filter geometries for a range ofdifferent
casting processes has indicated that the flow ofmetal and heat
losses through the filters are rather com-plex and should be
considered when using filters in thecasting processes. This paper
will present a number of casesof different types of filters modeled
and different processesand indicate some of the sensitivities of
the processes toboundary conditions imposed by the process.
5:05 PMComputer Heat Transfer Model for Directionally
Solidi-fied Castings: Deming Wang1; R. A. Overfelt1;
1AuburnUniversity, Mechl. Eng. Dept., 201 Ross Hall, Auburn
Uni-versity, AL 36849 USA Thermal transfer control is very
important indirectionally solidified (DS) castings. This paper
presentsa simple and efficient computer-aided heat transfer
simu-lation method to predict the thermal characteristics of
analloy sample in a special furnace for directional
solidifica-tion. A two-dimensional transient heat transfer by
radia-tion combined with conduction is developed to calculatethe
energy exchange between the symmetric furnace andthe sample. A
control volume technique is used to obtain aset of highly efficient
finite difference equations for heatconduction and heat radiation
with changeable view fac-tors. The model well simulates the
transient process of DScastings. The simulation results are
verified by a few mea-surable experimental results. Using the
two-dimensionalcomputer simulation model, many thermal properties
ofthe samples can be obtained, such as temperature distribu-tion,
solidification velocity, the shapes and positions of
theliquid/solid interface and thermal gradient at the inter-faces.
These are very important to analyze microstructureof DS casting
alloy, avoid casting defects and control thequality of DS
castings.
Tuesday AM Plenary Session9:00 AM–9:45 AM
Tuesday AM Room: St. Tropez/Monte CarloSeptember 25, 2001
Location: Hilton San Diego Resort
Session Chair: James W. Evans, University of California, Dept.
ofMatls. Sci. & Min. Eng., 585 Evans Hall, Berkeley, CA
94720-1760USA
KeynotePhase Field Methods for Modeling Microstructure: JamesA.
Warren1; 1National Institute of Standards and Technol-ogy, Metall.
Div. & Ctr. for Theoretl. & Computl. Matl.
Sci.,Gaithersburg, MD 20899 USA The phase field method has been
successfully employedas both a tool to model heterogeneous
materials and asnumerical method for calculating the motion of
interfacesand phase boundaries without explicitly tracking
thoseinterfaces. The method has been used to model a diversesuite
of problems describing the microstructural evolutionin materials.
These models are derived from thermodynamicarguments and symmetry
principles, and usually guaran-
tee positive local entropy production for systems out
ofequilibrium. Descriptions of how phase field methods canbe
applied to the problems of solidification, grain growth,and
electroplating will be presented.
Track A - Structure
Tuesday AM Room: St. TropezSeptember 25, 2001 Location: Hilton
San Diego Resort
Session Chair: Jim Warren, NIST, CTCMS & Metall.
Div.,Gaithersburg, MD 20899-8554 USA
9:45 AMMicroporosity Evolution and Interdendritic Fluid
Flowsduring Solidification: Adrian S. Sabau1; SrinathViswanathan1;
1Oak Ridge National Laboratory, Matls. &Cer. Div., Bldg. 4508,
MS 6083, Oak Ridge, TN 37831 USA The occurrence of microporosity
during metal casting isdue to the combined effects of
solidification shrinkage andgas precipitation. The governing
equations for fluid flowand hydrogen evolution indicate that
porosity formationand fluid flow are strongly coupled. However, in
most stud-ies on microporosity, it is considered that the porosity
for-mation does not influence the fluid flow in the mushy zone.In
this study, a computational methodology is presentedfor the
numerical simulation of microporosity evolutionand interdendritic
fluid flow. The solution algorithm pre-sented includes a fully
coupled, implicit treatment ofmicroporosity and local pressure in
the mushy zone. It isshown that neglecting the effect of porosity
formation onthe pressure in the mushy zone yields higher pressure
dropsand an over-prediction of final porosity. By its
growth,microporosity compensates partially for the
solidificationshrinkage, reducing the feeding demand. Therefore, in
or-der to accurately describe casting defects, comprehensivemodels
of fluid flow, heat transfer, solidification, must in-clude the
effect of microporosity as well.
10:10 AMCellular Automata Computer Model of
PolycrystallinePlastic Deformation: Alexander V. Spuskanyuk1; Yakiv
E.Beygelzimer1; Victor M. Varyukhin1; 1Donetsk Physical
&Technical Institute of the NAS of Ukraine, High Press.
Phys.& Adv. Tech. Dept., 72 R. Luxembourg St., Donetsk
83114Ukraine Effects stipulated by interdependence of microlevel
andmacrolevel of plastic deformation processes were analyzed.Using
computing mechanics instead of constitutive rela-tionships the
adequate computer models were used, whichwas opened by cellular
automata approach. By means ofnumerical experiments, the cellular
automata allowed tostudy the macrobehavior of the ensemble of cells
at themacrolevel depending on the local microscopic laws thatdefine
evolution of each cell and its interaction with theclosest
environment. A cellular model of the plastic defor-mation of
polycrystalline aggregate was proposed and com-prehensively
described. Representative volume of the de-formed solid body
deformed was described as a popula-tion of interconnected units
which, in turn, consisted of
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ix
lower scale level units. Sliding along the various
allowedsliding systems deforms simple units, which do not havean
internal structure. For consideration of stress distribu-tion
within the limits of components, the approach of self-consistent
field was used. Rotation of units and momentstresses connected with
it were taken into account. Resultsof computer experiments are
analyzed, software is de-scribed.
10:35 AM Break
10:50 AMSimulations of Microstructural Evolution: Martin
E.Glicksman1; Kegang Wang1; P. Crawford1; 1Rensselaer Poly-technic
Institute (CII-9111), Matls. Sci. & Eng., 110 8th St.,Troy, NY
12180-3590 USA Predicting microstructure evolution in alloys
remains akeystone of materials science. The mean-field theory
ofphase coarsening, in the (impractical) limit of zero
volumefraction, was first formulated by Lifshitz and Slyozov, andby
Wagner (LSW). Numerous attempts have been made toextend LSW theory
toward microstructures with nonzerovolume fractions. The successes
achieved with analyticaltheories, however, have been limited, due
primarily to thedifficulties of characterizing interactions among
particlesand the matrix, and accounting for stochastic variations
inthe microstructural locale surrounding each particle.
Suchtheories predict unrealistic particle size distributions(PSDs)
when compared with experimental observations.The importance of
large-scale simulation of microstructureswas realized with
concurrently increasing capability ofcomputer hardware and
software. Since the 1980s we for-mulated and solved multiparticle
diffusion equations tosimulate the dynamics of phase coarsening.
These simula-tions provide insight into the nature of diffusion
interac-tions and multiparticle stochastics. The rate
constants,PSDs, and higher-order correlations can all be extracted
bysimulation. “Snap shot” simulation techniques, developedrecently
permit study of microstructure size at various vol-ume fractions.
Gradually, a bridge has been built connect-ing fundamental theory
and experiment through computersimulations. Some recent examples of
progress in simulat-ing microstructure evolution will be
discussed.
11:15 AMAb Initio Calculations of Theoretical Tensile Strength
inMetals and Intermetallics: Mojmir Sob1; Ligen Wang1; Mar-tin
Friak1; Vaclav Vitek2; 1Institute of Physics of Materials,Zizkova
22, Brno 616 62 Czech Republic; 2University ofPennsylvania, Dept.
of MSE, 3231 Walnut St., Philadelphia,PA 19104-6272 USA Fully
self-consistent ab initio electronic structure calcu-lations of the
theoretical tensile strength in metals and in-termetallics loaded
uniaxially along several crystallo-graphic directions are performed
using the full-potentialLAPW method. It turns out that the
theoretical tensilestrength and elastic anisotropy at higher
strains are closelyconnected with the presence or absence of
higher-symme-try structures along corresponding deformation paths.
To-tal energy calculations show that all higher-energy
cubicstructures studied are locally unstable with respect to
tet-ragonal and/or trigonal deformation modes. In interme-tallics,
there may or may not be symmetry-dictated energyextrema
corresponding to cubic lattices depending on the
atomic ordering. However, other energy extrema along
thedeformation paths besides those required by symmetry oc-cur.
Configurations corresponding to energy minima onthe deformation
paths may represent metastable structuresthat can play an important
role in interfaces and other ex-tended defects. As a specific
example, tensile strength ofsingle-crystalline tungsten loaded
uniaxially along the[001] and [111] directions is analyzed.
Although tungstenis elastically nearly isotropic for small
deformations theo-retical tensile strength exhibits a marked
anisotropy. Thisanisotropy is explained in terms of structural
energydiferences between bcc, fcc and simple cubic structureswhich
occur on the calculated deformation paths. Theo-retical results
compare favorably with available experimen-tal value obtained for
tungsten whiskers grown along the[110] direction. Further examples
include computer simu-lations of a tensile test for
single-crystalline NiAl, wherethe theoretical tensile strength for
the “hard” orientation[001] differs very significantly from that
for the [111] orien-tation. Again, this anisotropy may be
understood in termsof higher-symmetry structures present or absent
along thedeformation paths.
11:40 AMModeling of Interdendritic Strain and
Interden-driticCracking Phenomena during Dendritic Solidification
Pro-cesses: Mostafa El-Bealy1; 1Material Processing Interna-tional,
100 Trade Centre Dr., #103, Champaign, IL 61820USA A
one-dimensional mathematical model to calculate theinterdendritic
cracking tendencies for low alloyed carbonsteel casting processes
is described. The model combinesan interdendritic strain model with
concept of the effect ofalloying element on the solidification
behaviour, segrega-tion of carbon, and therefore, critical
elementaryinterdendritic area EIA. A susceptibility of cracking of
dif-ferent steels is modelled by using El-Bealy approach.
Modelpredictions were performed to explain the effects of vari-ous
alloying elements on the solidification and crackingphenomena. Some
typical cases in conventional castingprocesses related to increase
cracking susceptibility arediscussed. It is shown that there is a
satisfactory degree ofcorrelation between prediction a practical
casting knowl-edge. Possible solutions to these problems based on
theadjustment of chemical composition are proposed.
Track B - Melting & Solidification -II
Tuesday AM Room: Portofino/MarseillesSeptember 25, 2001
Location: Hilton San Diego Resort
Session Chairs: Dan Cook, Virginia Commonwealth University,
Mechl.Eng. Dept., 601 W. Main St., Rm. 312, Box 843015, Richmond,
VA23284-3015 USA; Mark Jolly, University of Birmingham,
Birmingham,Great Britain B15 2TT UK
9:45 AMWax Injection in the Investment Casting Industry:
Jean-Christophe Gebelin1; Alexander Cendrowicz1; Mark R.
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Jolly1; 1The University of Birmingham, IRC in Matls.,Edgbaston,
Birmingham, W. Midlands B15 2TT UK Injection of wax patterns is the
first stage of the multi-stage process of investment casting. The
quality of the finalcasting and its dimensional accuracy is highly
dependenton this stage of the process. Pattern waxes used in the
in-dustry behave in a complex visco-elastic-plastic manner.The
modelling of such material behaviour is therefore notsimple. In
this paper a number of configurations of die willbe shown in which
the injection of the wax has been car-ried out for a range of
processing conditions. Some of thedies are transparent and the
movements of wax front ob-served can be compared with those
predicted by simula-tion. Surface defects in final components will
also be shownand compared with the location predicted by
simulationsoftware. Some discussion will be presented on the
limita-tions of the software used and the time-scales achieved
forpractical use as a design tool within the foundry
environ-ment.
10:10 AMMicro/Macro Modeling of Ingot Cooling Processes for
Ni-Cu-S Alloys: Apostle Mouchmov1; Mark Cross1; KoulisPericleous1;
1University of Greenwich, Sch. of Compg. &Mathl. Sci., 30 Park
Row, Greenwich, London SE10 9LS UK Copper–nickel–sulphide alloys
are typically cooled andsolidified in 4, 8 and 16 tonne ingots.
These ingots exhibita variation of grain size distribution and
macro segrega-tion of the prime alloy components throughout. The
formeris assumed to be primarily due to the dominant
relationbetween grain growth rate and the cooling profile,
whilstthe latter is heavily influenced by buoyancy driven
residualconvection. The objective of this research program is to
ex-amine the extent to which it is possible to develop a
‘broadbrush’ computational model of this ingot cooling process,that
can predict some ‘integral’ measure of the grain size(e.g. average
diameter) and the macro-segregation as a func-tion of operating
conditions. A computational modelingsoftware framework, PHYSICA+ is
used to simulate thecomplex process of ingot casting, which
involves couplingbetween different physical phenomena. The entire
modelinvolves: (i) a ‘broad brush’ grain growth model that couldbe
used in the prediction of micro/macro-structure of alloyingot
cooling processes, (ii) a heat transfer and solidifica-tion model
which takes into account a second phase trans-formation of Ni3S2 to
heazle-woodite, and (iii) NS fluidflow simulation which provides a
good basis for furthermicro/macro segregation modeling. At this
stage some re-sults of the 3D convection driven thermal cooling and
so-lidification profiles will be shown, together with the
‘inte-gral’ model for the grain size prediction.
10:35 AM Break
10:50 AMComparison of Numerical Models of Solidification
Be-havior in Direct Chill Casting with Experiments: Christo-pher J.
Vreeman2; David Schloz3; Matthew John M. Krane1;1Purdue University,
Sch. of Matls. Eng., W. Lafayette, IN47907 USA; 2Boeing North
American, Rocketdyne Div., 6633Canoga Ave., Canoga Park, CA 91309
USA; 3Wagstaff, Inc.,3910 N. Flora Rd., Spokane, WA 99216 USA
Numerical results from a continuum mixture model ofthe Direct Chill
casting process is compared to experimen-
tal results from industrial scale aluminum billets. Themodel,
which includes the transport of free-floating solidparticles, is
used to simulate the effect of a grain refiner onmacroseg-regation
and fluid flow. It is applied to an Al-6wt%Cu alloy and the effect
of casting speed, grain refiner,and assumed mushy zone permeability
on predictedmacrosegregation, sump profile, and temperature fields
arepresented. Three 45 cm diameter billets were cast
underproduction conditions with and without grain refiner andat two
casting speeds. Temperature and composition mea-surements and sump
profiles are compared to the numeri-cal results. The comparison
shows qualitative agreementand limitations of application of the
model to industrialprocesses are discussed.
11:15 AMTwo-Phase Predictive Finite-Element Flow Model
forSemi-Solid Slurries: Frédéric Pineau1; 1National ResearchCouncil
Canada, Indl. Matls. Inst., Proc. Modlg. & Instrm.,75 de
Mortagne Blvd., Boucherville, Québec J4B 6Y4 Canada Semisolid metal
alloys have a special microstructure ofglobular grains suspended in
a liquid metal matrix. Thisparticular physical state of the matter
can be exploited toproduce near-net-shape parts with improved
mechanicalproperties. However, the behavior of the slurry is
stronglyinfluenced by the local solid fraction and state of
agglom-eration. Different flow instabilities associated with the
com-bined flow and solidification process result, which
makedifficult the application of semisolid processing in the
cast-ing industry. Moreover, the rheology of semisolid materialsis
not well understood. Most of the theory has been derivedfrom
experimental data, which are somewhat difficult tomeasure. A model
that accounts for the multiphase natureof the slurry is required to
get more insight into such com-plex flows. This paper thus
describes a mixture model forsemisolid slurries. It assumes that
the mixture of liquid-solid components behaves as a single fluid as
far as overallmass and momentum balances are concerned. The
cou-pling force between the phases is derived on the assump-tion
that the slurry is a fluid saturated isotropic media. Theproposed
methodology is implemented in a finite elementcode. The filling of
an industrial-scale capillary flow vis-cometer is investigated
numerically. Segregation patternsare obtained and discussed.
11:40 AMCFD Simulation of Continuous Charging and Melting
ofSmall Metallic Particles in a Melting Reactor: StefanPirker1;
Oszkar Biro3; Philipp Gittler1; Peter Mittag2; Ber-nard Aigner2;
1Johannes Kepler University, Altenbergerstr.69, Linz A-4040
Austria; 2VOEST ALPINEIndustrieanlagenbau GmbH, Postfach 3, Linz
A-4031 Aus-tria; 3Technical University Graz, Kopernikusgasse 24,
8010Graz, Austria This paper considers CFD modelling of processing
andmelting of small metallic particles by means of
electricalheating. The particles fall continuously onto a liquid
metalbath which is heated by an electric arc. After melting of
theparticles liquid metal is tapped. The charging behavior ofthe
particles in the supply unit as well as in the reactorfreeboard is
studied by means of Euler-Euler granular simu-lations. The flow
situation in the metal bath due to gasinjection and magnetic fields
is calculated by combining
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Navier-Stokes and Maxwell solvers. The macroscopic melt-ing
process occurring during the continuous charging ofthe particles is
studied by kinetic laws for melting reac-tions. The temperature
field is evaluated by balancing heatsources due to Joule’s heating
and heat losses due to latentheat of melting as well as convection
and radiation. As aresult of these simulations the fully
three-dimensional flowfields of particles and gas in the atmosphere
is obtained.Furthermore the flow field as well as the magnetic
field inthe metal bath can be studied. As a main result the
three-dimensional concentration field of the still unsolved
par-ticles in the liquid metal can be evaluated.
12:05 PMNumerical Simulation of Wax Pattern Dimensions in
In-vestment Casting: Adrian S. Sabau1; Srinath Viswanathan1;1Oak
Ridge National Laboratory, Matls. & Cer. Div., Bldg.4508, MS
6083, Oak Ridge, TN 37831 USA Dimensional Changes between a pattern
die and its cor-responding investment cast part occur as a result
of com-plex phenomena such as thermal expansion/contractionand hot
deformation (elastic, plastic, and creep) during theprocessing of
the pattern material (wax), mold material(shell), and solidifying
alloy. Determining the pattern tool-ing dimensions is crucial to
the dimensional control of theinvestment casting process. To date,
there are no computa-tional methodologies available for predicting
dimensionalchanges during investment casting. This paper deals
withthe evaluation of wax pattern dimensions, which is oneimportant
factor in determining the pattern tooling dimen-sions in investment
casting. Cerita 29-51, an industrial waxis considered in this
study. The wax pattern dimensionsare affected by its thermophysical
and thermomechanicalproperties, restraint of geometrical features
by the metaldie, and process parameters such as dwell time, platen
tem-perature, injection pressure and injection temperature.
Nu-merical simulation results for the wax pattern dimensionsare
compared with experimental measurements. Criticalvariables that
determine dimensional changes associatedwith the wax system are
identified.
Tuesday PM Plenary Session2:00 PM–2:45 PM
Tuesday PM Room: St. Tropez/Monte CarloSeptember 25, 2001
Location: Hilton San Diego Resort
Session Chair: Koulis Pericleous, University of Greenwich,
GreenwichMaritime Campus, Greenwich, London SE10 9LS UK
KeynoteComputational Modelling of Metals Reduction
Processes:Phil Schwarz1; 1CSIRO Minerals, Box 312, Clayton
S.,Victoria 3163 Australia This paper reviews the status of
computational model-ling of a variety of common metals reduction
processes,namely the blast furnace, rotary kiln and fluidised
bed,and one new process not yet commercialised, namely
smelt-ing-reduction as in the HIsmelt® Process. In each case,
thelast decade has seen the emergence of the capability to
simu-
late the processes using multi-phase reacting computationalfluid
dynamics techniques. In some cases this capability isstill in the
process of being developed, and the next fewyears will see the
maturing of the modelling techniques. Asthey become established, it
will be possible to apply themto further refine the older
technologies such as blast fur-naces and rotary kilns, and assist
in the optimisation,commercialisation and acceptance of the newer
technolo-gies such as fluidised bed and molten bath reduction.
Thedevelopment of a computational fluid dynamic model ofbath
smelting-reduction is described in some detail to il-lustrate how a
large number of complex and interactingphenomena can be
successfully simulated within a CFDframework.
Track A - CFD Modelling - II
Tuesday PM Room: St. TropezSeptember 25, 2001 Location: Hilton
San Diego Resort
Session Chairs: Phil Schwarz, CSIRO Minerals, Box 312, Clayton
S.,Victoria 3163 Australia; Pascal Gardin, IRSID,
Maizieres-les-MetzFrance
2:45 PMModelling of Raceway Hysteresis: Govind S. Gupta1;
S.Sarkar1; M. G. Basavaraj1; P. D. Patil2; 1Indian Institute
ofScience, Dept. of Metall., Bangalore 560 012 India;
2IndianInstitute of Science, Dept. of Cheml. Eng., Bangalore 560012
India Previous experimental study on raceway size hysteresison
two-dimensional cold model showed that the interpar-ticle and
wall-particle friction had a very large effect on theraceway size.
Existing literature correlations for racewaysize ignore the
frictional effects. It has also been shown inthe present study that
their applicability to the ironmakingblast furnace is questionable.
To take into account the effectof friction on the raceway size a
stress analysis has beendone for the raceway region. The partial
differential equa-tions for the stresses have been developed and
solvedcomputationally. The frictional forces were obtained interms
of stresses. To predict the raceway size a force bal-ance was done
for the raceway zone considering the pres-sure force, the
frictional force and the bed weight. The re-sulting equations from
the force balance are able to de-scribe the raceway hysteresis
phenomena correctly alongwith the raceway size. A two dimensional
experimental setup has been fabricated in order to validate the
computerpredictions. Predicted values agree well with the
experi-mental values. A correlation has been developed to
predictthe raceway size.
3:10 PMLifetime Prediction of Pneumatic Conveyor Bends withthe
Aid of Computational Models: Mayur K. Patel1; RobertHanson1;
1University of Greenwich, Ctr. for Numl. Modlg.& Proc. Analy.,
30 Park Row, Greenwich SE10 9LS UK The puncture of pneumatic
conveyor bends in industrycauses several problems. Two important
factors are: (1)Escape of the conveyed product causing health and
dust
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hazard and (2) Repairing and cleaning up after
puncturesnecessitates shutting down conveyors, which will affectthe
operation of the plant, thus reducing profitability. Bendsin
pneumatic conveying systems tend to wear out and punc-ture first
since particles generally strike the bend walls withlarger
intensity than straight pipe sections. Current mod-els for bend
lifetime prediction are inaccurate as they fail toaccount for key
parameters that are of fundamental impor-tance to the progression
of the wear. The provision of anaccurate predictive method would
lead to improvementsin the structure of the planned maintenance
programmes,thus reducing unplanned shutdowns. The paper reportsthe
first phase of a study undertaken to develop and imple-ment a CFD
based engineering tool to predict the lifetime ofconveyor bends for
two- and three-dimensional test cases.The model used is based on
Eulerian and Lagrangian meth-ods. It is unique in that the erosion
due to the particle im-pacts is accounted for within a CFD
framework, thus tak-ing into account angle of attack and impact
velocity, ensur-ing more realistic predictions of the wear profile
and theirgrid dependency and sensitivity to the inlet particle
distri-butions.
3:35 PM Break
3:50 PMA Parametric Study of Oxy-Fuel Burners in
SecondaryAluminum Melting: Madhu Huggahalli1; Neeraj Saxena1;Ken
Grieshaber2; Jerry Bernardski2; David Stoffel2; 1BOCGases, Tech.,
100 Mountain Ave., Murray Hill, NJ 07974USA; 2BOC Gases, 575
Mountain Ave., Murray Hill, NJ07974 USA The use of oxy-fuel burners
in secondary aluminum melt-ing applications offers several
advantages including re-duced fuel consumption, faster charge to
tap times andlower NOx emissions. Their successful, safe and
economi-cal use in a furnace depends on several factors and
consid-erations such as burner and flue placement, metal
circula-tion, charge practices and the type of refractory used in
thefurnace. These factors required in the successful conver-sion of
furnaces from air-fuel to oxy-fuel based burners arediscussed in
detail in this paper. Critical parameters areidentified and
examined using computational fluid dynam-ics (CFD) simulations.
Parameters are estimated via labo-ratory testing and validated
through trials performed atcommercial installations. Guidelines and
a simplified ap-proach to estimate à priori the economic impact of
convert-ing from air-fuel to oxy-fuel are presented. The final
prod-ucts of this research are simplified and validated tools
formodeling aluminum furnaces. These include improved heatand
energy balance models and parameterized CFD solu-tions which allow
rapid customization to individual fur-nace configurations. These
tools provide field engineerswith immediate and accurate
predictions of performance,allowing for repeated precise scenario
analyses.
4:15 PMComputational Modelling of Vortex Formation in the
LeadRefining Kettle: Suman Kumar1; Chris Bailey1; MayurPatel1; A.
W. Piper2; M. Cowling2; R. A. Forsdick2; 1Univer-sity of Greenwich,
30 Park Row, Greenwich, SE10 9LS UK;2Britannia Refined Metals,
Ltd., Northfleet, UK The refining of lead bullion takes place in
hemisphericalvessels (known as kettles) of various sizes. It is
normal
practice to remove impurity elements (i.e. copper,
silver,bismuth, antimony, etc.) sequentially, by the addition
ofreagents. This process has been in operation for many yearsin
refineries all over the world. Unfortunately very little
isunderstood about the actual mixing and refining processtaking
place in these kettles. This paper will present a de-tailed
modelling analysis of this process, where computa-tional and
physical modelling techniques have been used.The computational
fluid dynamics (CFD) techniques usedto model fluid mixing by
impellers will be discussed andresults will be presented comparing
CFD data with plantdata. Also discussed will be the modelling
techniques usedto simulate the reactions taking place in the vessel
duringimpurity removal.
4:40 PMCFD Modeling of Solids Suspensions in Stirred Tanks:Lanre
Oshinowo1; André Bakker2; 1Hatch, 2800 SpeakmanDr., Mississauga,
Ontario L5K 2R7 Canada; 2Fluent, Inc.,10 Cavendish Ct., Lebanon, NH
03766 USA Mechanical agitation is widely used in process
industryoperations involving solid-liquid flows. The typical
pro-cess requirement is for the solid phase to be suspended forthe
purpose of dissolution, reaction, or to provide feed uni-formity.
If these vessels are not functioning properly, byinadequately
maintaining suspension, the quality of theproducts being generated
can suffer. Associated with theoperation of these units is a need
to maintain the suspen-sion at the lowest possible cost. The
challenge is in under-standing the fluid dynamics in the vessel and
relating thisknowledge to design. CFD modeling can provide insight
toboth the multiphase transport and the design parameters.An
understanding of the parameters that govern the just-suspended
impeller speed, Njs, and the distribution of sol-ids, is critical.
Recent advances in computational fluid dy-namics allow for the
modeling of multiphase systems, suchas the liquid-solid mixtures
discussed here. Of particularinterest is the Eulerian multiphase
model, which uses sepa-rate sets of Navier-Stokes equations for the
liquid and sol-ids (or granular) phases. Incorporating moving
impellermodeling techniques, such as, the sliding mesh
method,provides a rigorous estimate of the solids suspension
be-havior. This paper will assess the current design param-eter Njs
in the context of scale-up and compare it to thequality of solids
dispersion as a means of assessing correctscale-up in suspension
tank design. The work presentedincludes a study of a 45°
pitched-blade turbine and a hy-drofoil impeller. Both single and
dual impeller operationhave been evaluated. For a given impeller
style in a fixedvessel, D/T and C/T are varied to explore
suspension flowpatterns at Njs. The settled solids fraction for
speeds belowNjs, and the cloud height for impeller speeds above
Njswere studied. The CFD results correspond well with ex-perimental
literature data on velocity distribution and cloudheight.
5:05 PMWater Model and Numerical Study on the Spout Heightin a
Gas Stirred Vessel: Diancai Guo1; G. A. Irons1;1McMaster
University, Steel Rsrch. Ctr., 1280 Main St.,Hamilton, Ontario L8S
4L7 Canada The average spout height and width produced by bot-tom
gas injection in a water model of a steel ladle were
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measured with an image processing technique. It was re-vealed
that the spout height could be described by aGaussian curve. A
combined SIMPLE-VOF model was de-veloped to simulate the liquid
surface and flow. The resultsshowed that, though the model produced
reasonable ve-locity distributions and free surface positions, the
spoutheight due to the dynamic head of the rising liquid
wassubstantially lower than observed, indicating that thebubble
dynamics at the bath surface play an important rolein spout
height.
Track B - Thermo-MechanicalModelling - I
Tuesday PM Room: Portofino/MarseillesSeptember 25, 2001
Location: Hilton San Diego Resort
Session Chairs: Brian G. Thomas, University of Illinois–Urbana,
Dept.of Mechl. & Indl. Eng., Urbana, IL 61801 USA; Danny
Wheeler, NIST,Gaithersburg, MD 20899-8555 USA
2:45 PMThick Yield Surface: An Approach to the Processing
ofComputer Experiments on Polycrystalline Deformation:Yan E.
Beygelzimer1; Alexander V. Spuskanyuk1; VictorVaryukhin1; 1Donetsk
Physical & Technical Institute of theNAS of Ukraine, High
Press. Phys. & Adv. Tech. Dept., 72R. Luxembourg St., Donetsk
83114 Ukraine The main idea of the report is that the yield surface
canbe presented as thick, “foamed surface” with dimensional-ity
exceeding two. By other words, perhaps, the yield sur-face is
fractal, i.e. it belongs to the geometric objects withfractional
dimensionality. Apparently, fractal structure ofthe yield surface
is determined by the fractal structure ofnatural materials.
Besides, the “cloud of internal stresses”term is introduced to
describe the stress distribution in RVE.Its plastic flow is
determined by the interaction of this cloudwith the thick yield
surface. Thick yield surface and inter-nal stress cloud concepts
allow to determine the additionalcorrelation between
micromechanical models of polycrys-tals and phenomenological theory
of plasticity.
3:10 PMModel for Stress, Temperature and Phase Transforma-tion
Behaviour of Steels on Run-Out Table in Hot StripMill: Heung Nam
Han1; Jae Kon Lee1; Hong Jun Kim1;Young-Sool Jin1; 1Pohang Iron
& Steel Co., Ltd. (POSCO),Sheet Prod. & Rsrch. Grp., Techl.
Rsrch. Labs., Pohang POBox 36, 1 Koedong-dong, Nam-ku, Pohang-shi,
Kyungbuk790-785 Korea A mathematical model was developed
considering non-symmetric cooling and stress distribution in both
thick-ness and width direction of strip on a run-out table of
hotstrip mill. In order to solve a transient heat transfer
equa-tion including the heat evolved from phase transforma-tion, a
finite difference method coupled with thermody-namic and kinetic
analyses was applied. The heat capac-ity of each phase and heat
evolution due to phase transfor-mation were obtained from the
thermodynamic analysis ofthe Fe-C-Mn-Si system based on a
sublattice model. The
phase transformation kinetics of the steels was derived byusing
continuous cooling experiments and the thermody-namic analysis.
Heat transfer coefficients of strips on therun-out table were, by
applying an inverse method, deter-mined from actual mill data under
various cooling condi-tions. As for the stress analysis, the
density change of stripdue to cooling and phase transformation and
the transfor-mation induced plasticity were considered. A
constitutiveequation for the transformation induced plasticity,
whichis related to the phase transformation kinetics and the
ap-plied stress, was newly suggested. A finite element methodwas
adopted to calculate the deformation behaviour of stripon run-out
table.
3:35 PM Break
3:50 PMThermo-Mechanical Coupling Finite Element Analysisof
Sheet Metal Extrusion Process: Zhanghua Chen1; C. Y.Tang1; T. C.
Lee1; 1The Hong Kong Polytechnic University,Dept. of Mfg. Eng.,
Hung Hom, Hong Kong, China In sheet metal forming process, the
forming limit andstrain distribution are governed by plastic
instability andfracture following strain localization. It has been
provedthat the temperature gradient caused by plastic deforma-tion,
heat transfer, and friction between sheet and tools isone of
crucial factors to induce the strain localization inhigh speed
metal forming processes. In this paper, a nu-merical simulation of
the sheet metal extrusion process hasbeen conducted by using
thermal-mechanical coupling fi-nite element method. In the
investigation, the sheet metalextrusion is assumed to be a
non-isothermal and elasto-plastic process. The material of
workpiece is SS400 steelwhich is the same as that used in
experiment. The bound-ary energy dissipation due to heat convection
has beentaken into account. Bishop’s step-wise decoupled strategyis
adopted to handle coupling between mechanical defor-mation and the
temperature variation. This technique hasbeen proven to be robust
and efficient for large thermal-plastic deformation computation. By
adopting this ap-proach only the pure mechanical parts of the weak
formshave to be consistently linearized since the coupling termsare
held constant during the iteration. In order to avoidlocking
deficiency that frequently exhibited in classicaldisplace-based
finite element method, an improved largedeformation mixed finite
element method has been used tosolve this near-incompressible metal
forming problem. Thestandard Newton-Raphson iteration method
together withthe corresponding consistent tangent operator has
beenadopted to solve nonlinear algorithmic equations. In ther-mal
phase, the transient heat transfer finite element methodtogether
with the Crank-Nicholson algorithm has beenemployed to determine
the temperature field. The total timefor extrusion process is
specified to be 0.4 second. Usi