30th March 2009
0.1 Air heater . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20.1.1 Building geometry . . . . . . . . . . . . . . . . . . . . . . 30.1.2 Setting boundary condition types . . . . . . . . . . . . . . 70.1.3 Setting Fluent parameters . . . . . . . . . . . . . . . . . . 80.1.4 Performing calculations . . . . . . . . . . . . . . . . . . . 90.1.5 Final remarks . . . . . . . . . . . . . . . . . . . . . . . . . 10
0.2 Cyclone. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110.2.1 Building geometry . . . . . . . . . . . . . . . . . . . . . . 110.2.2 Setting boundary condition types . . . . . . . . . . . . . . 150.2.3 Meshing geometry . . . . . . . . . . . . . . . . . . . . . . 160.2.4 Setting Fluent parameters . . . . . . . . . . . . . . . . . . 170.2.5 Performing calculations . . . . . . . . . . . . . . . . . . . 19
0.1 Air heater
This example shows how to simplify 3D geometry of the real object and performcalculation in 2D space. Air heater geometry is given in Figure 1. The air streamflows from left to the right. There are only two opening in the heater, inlet (left)and outlet (right). The other sides (front, back, top, bottom) are insulated walls.Inside the heater 3 cylindrical pipes are positioned perpendicular to the flow.Data of the operation of the heater are given in Table 1.The flow patern in such configuration of the heater in any cross section (alignedwith flow direction) is almost the same. The width of the heater is high enoughto neglect influence of the side walls (front and back) on the flow in the middlepart of the heater. Hence we can simulate flow in the heater with good accuracyassuming 2D geometry (see the heater cross section in the Figure 2, we do notutilize symmetry of the cross section geometry since we want later to analyze
different cylinder alignments). Even for simplified geometry flow over cylindersemerge to be complex, with stagnation zones and revers flow close to the cylin-ders. That feature require proper treatment of the mesh. First of all it needsto be symmetric as the flow is symmetric. The best is to try generate fullystructured mesh and if possible with cells edges aligned with the direction ofthe flow. This is not possible in all area of the flow, but at least at the cylinderboundaries cells alignment should follow flow direction.
Figure 1: Air heater.
air flow 5 m/sair inlet temperature 300 Kthermal input at each heater 1.6 kWwalls thermal condition 0 kW (isolation)
Table 1: Air heater set up parameter
0.1 m 0.1 m
Figure 2: Air heater cross section - dimensions.
0.1.1 Building geometry
As already mentioned we require structured mesh made of Quad type elements.In order to use Quad elements we need earlier to plan how to divide geometryin topological faces which later are easy to mesh. Figure 3 shows proposition oftopological division of the air heater geometry. One can recognize that all facesposses 4 edges what allows to mesh them easily with Quad elements.
Figure 3: Air heater topological division of the geometry.
See below listing of the geometry creation procedure.
Geometry → Edge → Create Edge → ArcSelect method: Radius, Start Angle, End AngleEnter Radius = 0.02, Start Angle = -45, End Angle = 45Press Apply
Enter Radius = 0.02, Start Angle = 45, End Angle = 135Press Apply
Enter Radius = 0.02, Start Angle = 135, End Angle = 225Press Apply
Enter Radius = 0.02, Start Angle = 225, End Angle = 315Press Apply
Geometry → Vertex → Create VertexEnter X = 0.05, Y = -0.05, Z = 0Press Apply
Enter X = 0.05, Y = 0.05, Z = 0Press Apply
Enter X = -0.05, Y = 0.05, Z = 0Press Apply
Enter X = -0.05, Y = -0.05, Z = 0Press Apply
create edges around tube
Geometry → Edge → Create Edge → StraightSelect with mouse (holding Shift button) created Vertices (only 2 at the sametime)Press Apply
Repeat operation (8 times) in order to get effect shown in Figure 4.
Figure 4: Edges around the tube.
create faces around tube
Geometry → Face → Form Face → WireframeSelect with mouse (holding Shift button) created Edges (only 4 at the sametime)Press Apply
Repeat operation (4 times) in order to get effect shown in Figure 5.
Figure 5: Faces around the tube.
mesh faces around tube, first set distribution of the nodes on the edges
Mesh → Edge → Mesh EdgesSelect with mouse (holding Shift button) edges creating tubeDeselect GradingSelect Spacing and enter Interval size = 0.001Select Option MeshPress Apply
set distribution of the nodes on the edges radially connected with tubeSelect with mouse (holding Shift button) radial edgesSelect GradingSelect Type First Length and enter Length = 0.001Select Spacing and enter Interval count = 20Select Option MeshPress Apply
mesh faces around tube
Mesh → Face → Mesh FacesSelect with mouse (holding Shift button) all 4 facesSelect SchemeSelect Elements → QuadSelect Type → MapPress Apply
The mesh generated should have similar form of that shown in Figure 6, howevernumber of elements is different.make 2 copies of mesh around the tubes
Geometry → Face → Move/Copy/AlignSelect with mouse all facesSelect Copy and enter 2 (this is number of copies)Select Operation → TranslateEnter X = 0.1, Y = 0, Z = 0
Figure 6: Mesh around the tube.
The effect of operation is shown in Figure 7, (number of elements is different).
Figure 7: Copied mesh around the tubes.
Coping of the faces in the way presented above result in double Edges lying atthe same position between copied meshes. If we did not set them as interfacesFluent will treat them as walls (no flow between these part of mesh). Simplesolution to this problem is connecting this edges.
Geometry → Edge → Connect EdgesSelect with mouse all double faces (lying at the same position)Select RealPress Apply
As the result the double edges will be connected and one of them be deleted.Remaining part of the mesh is generated by simply creating rectangular faces.Since procedure is very simple only picture showing consequent steps is givenin Figure 8.
Figure 8: Steps of creating air heater geometry.
0.1.2 Setting boundary condition types
The last step in Gambit is setting boundary condition types.Zones → Specify Boundary TypesCheck (Add)Enter, Name: inletSelect Type → VELOCITY INLETPick Entity : Edges, edge representing inlet to the cyclone, see Figure 2press Apply
Zones → Specify Boundary TypesCheck (Add)Enter, Name: outletSelect Type → OUTFLOWPick Entity : Edges, edge representing outlet from the cyclone, see Figure 2press Apply
Zones → Specify Boundary TypesCheck (Add)Enter, Name: sidesSelect Type → WALLPick Entity : Edges, edges creating top and bottom wall of the heaterpress Apply
Zones → Specify Boundary TypesCheck (Add)
Enter, Name: heater 01Select Type → WALLPick Entity : Edges, edge creating first pipe of the heaterpress Apply
Zones → Specify Boundary TypesCheck (Add)Enter, Name: heater 02Select Type → WALLPick Entity : Edges, edge creating second pipe of the heaterpress Apply
Zones → Specify Boundary TypesCheck (Add)Enter, Name: heater 03Select Type → WALLPick Entity : Edges, edge creating third pipe of the heaterpress Apply
export generated mesh into the file
File → Export → Mesh...Enter File Name: heater.mshCheck (Export 2d Mesh)press Apply
0.1.3 Setting Fluent parameters
After reading mesh generated with Gambit we have to define all the models,material properties, boundary conditions and solver parameters required tosimulate operation of heater. Most of the parameter in Fluent can be left asdefault. The procedure listed below shows mainly these settings which needs tobe changed.
Read mesh file (mesh files have extension msh) created in previous section.File → Read → Case...Define solver settings as default.Define → Models → Solver...Set turbulence modellDefine → Models → Viscous...Select k − ε Standard turbulence model with option Standard Wall FunctionDefine material properties Define → Materials...Check material properties for airEnter Density (kg/m3) equal to 1.225Enter Cp (j/kgK) equal to 1006.43
Enter Thermal Conductivity (W/mK) equal to 0.0242Enter Viscosity (kg/ms) equal to 1.7894e-5Confirm changes pressing Change CreateClose Material panel pressing CloseDefine boundary condition Define → Boundary Conditions...Select Zone → inlet, press SetEnter Velocity Magnitude (m/s) equal to 5Enter Temperature (K) equal to 300Select Turbulence Specification Method → Intensity and Hydraulic DiameterEnter Turbulence Intensity (%) equal to 10Enter Hydraulic Diameter (m) equal to 0.4Accept settings pressing OKSelect Zone → heater 01, press SetFrom Thermal tab for Thermal Conditions select Heat FluxEnter Heat Flux (W/m2) equal to 16000Accept settings pressing OKPress Copy from Boundary Condition panelUnder From Zone select heater 01Under To Zone select heater 02, heater 03Press CopyAccept selection pressing OKClose Copy BCs panel pressing CloseClose Boundary Conditions panel pressing Closeset up solver parameters
Solve → Controls → Solution...assume all default settings
Initialize solution Solve → Initialize → Initialize...Press Init and close Solution Initialization panelSet solution monitoring option Solve → Monitors → Residual...Under Option select PlotFor Residual → continuity → Convergence Criterion enter value equal to 10e-9Accept settings pressing OKsave Fluent settings parameter in case file (case files have extension .cas) File→ Write → Case..., enter file name and accept settings pressing OK
0.1.4 Performing calculations
Herewith we assume that Fluent is open and case file with heater is read.
Type in Fluent command window it 100, (this command executes 100 iterations)Observe in Fluent result window residuals of the solved equations
All calculated variable can be displayed in the Fluent result window in the formof colored field. Additionally profiles of these variables can be created at arbi-tral position inside computational domain. The result window can be zoomedin and out in order to observe particular regions of the flow. Displayed variablescale can be adjusted to arbitral ranges.
Solution variables can be displayed as follow,Select Display → Contours...From Option select Filledstatic pressure will be displayed
From Contours of, select Pressure... → Static PressurePress Display
Repeating procedure above one can display all solution variables.
Creating profile line for extracting data
Herewith we will create line cutting the cross section of the domain at the po-sition 0.5 m from the inlet to the heater. Line will be aligned vertically andperpendicular to the flow direction.
Surface → Line/Rake...From Type select Rake, advantage of using Rake instead of Line is that we prede-fine number of points at which values are plotted or printed, in case of using Linenumber of points for dense meshes can be large, additionally Line extract valuesfrom the closes volume cell center, when Rake interpolate values from closes vol-
ume cells and calculate it for position at which point of a rake is placed.
For Number of Point enter required value, we suggest at least 20, but that stronglydepend on the problem solved, variable printed and position of the RakeFrom Points enter,x0(m) = 0.1, x1(m) = 0.5y0(m) = 0, y1(m) = 0.2For New Surface Name enter desired name of the rake and press CreateClose Line/Rake Surface panel pressing Close
Created Rake can be used from Plot → XY Plot... panel in order to plot, printor write to a file solution variables placed on the defined by rake positions.
0.1.5 Final remarks
Experienced user can realize that presented here case is not trivial one. Firstof all turbulence model used here is not always suitable for such a flows sinceReynolds number is at the very low level of 11 000. There is completely neglected
discussion of the near wall treatment and simply standard wall approach isutilized. However main purpose of this tutorial is to show how to relatively easycreate structured mesh for the geometry which automatic mesh generator arenot able to handle such meshes.One can try to build geometry with different heater alignments and observe howthat influence, the flow, pressure drop, and temperature profile at the outlet ofthe heater.
In many industrial processes emerge a need of cleaning gases from dispersedinert particles suspended within gas (eg. removal of flying ash from flue gasesin industrial coal fired boilers). Easiest and most commonly used method ofseparation takes advantage of gravitation forces. Device which work on thisbasis is a cyclone. With this tutorial we build simple cyclone geometry, mesh it,and run Fluent simulations. Instead of flue gases we will use air stream pollutedwith ash. Data for boundary conditions are given in Table 2.
air flow 0.27 m3
air flow temperature 50 0Cash mass flux 0.001 kg/smin. particle diameter 1 µmmax. particle diameter 300 µmmean particle diameter 150 µmspread parameter 2.8ash density 2100 kg/m3
Table 2: Cyclone running parameter
Figure 9 shows cyclone dimensions. Geometry of the cyclone is build in Gambitusing volume primitives. Figure 10 shows all volumes used to build the cyclonewhich are connected using boolean operations.
0.2.1 Building geometry
Procedure of building the cyclone geometry is very simple. First we createand move in the right position volume primitives presented in Figure 10. Nextboolean summation and subtraction is used to unite all primitives in order tocreate one volume representing a cyclone. See below listing of the geometry cre-ation procedure. Listing shows order of operations to be carried out in Gambit.
Geometry → Volume → Create Volume → CylinderEnter Height = 0.5, Radius 1 = 0.3, Radius 2 = 0.3press Apply
Figure 9: Cyclone dimensions.
Geometry → Volume → Create Volume → FrustumEnter Height = 1.0, Radius 1 = 0.3, Radius 2 = 0.3, Radius 3 = 0.1press Apply
Geometry → Volume → Move/Copy/AlignSelect with the mouse created frustum: Pick Volume 2Check Move, TranslateEnter X = 0, Y = 0, Z = 0.5press Apply
Geometry → Volume → Create Volume → CylinderEnter Height = 0.05, Radius 1 = 0.1, Radius 2 = 0.1
Figure 10: Volume primitives for Cyclone.
Geometry → Volume → Move/Copy/AlignSelect with the mouse created cylinder: Pick Volume 3Check Move, TranslateEnter X = 0, Y = 0, Z = 1.5press Apply
Geometry → Volume → Create Volume → CylinderEnter Height = 0.15, Radius 1 = 0.2, Radius 2 = 0.2press Apply
Geometry → Volume → Move/Copy/AlignSelect with the mouse created cylinder: Pick Volume 4
Check Move, TranslateEnter X = 0, Y = 0, Z = 1.55press Apply
Geometry → Volume → Create Volume → CylinderEnter: Height = 0.8, Radius 1 = 0.1, Radius 2 = 0.1press Apply
Geometry → Volume → Move/Copy/AlignSelect with the mouse created cylinder: Pick Volume 5Check Move, TranslateEnter X = 0, Y = 0, Z = -0.2press Apply
Geometry → Volume → Create Volume → BrickEnter Width = 0.2, Depth = 0.7, Height = 0.2press Apply
Geometry → Volume → Move/Copy/AlignSelect with the mouse created cylinder: Pick Volume 6Check Move, TranslateEnter X = 0.2, Y = 0.35, Z = 0.1press Apply
Geometry → Volume → Boolean Operations → UniteSelect with the mouse all the volumes except last created (Volume 6): Pick Vol-ume 1,Volume 2,Volume 3,Volume 4,Volume 5press Apply
Geometry → Volume → Boolean Operations → SubtractSelect with the mouse the volumes which is result of last operation: VolumeVolume 1Select with the mouse remaining volume: Subtract Volume Volume 5Check Retain under Subtract Volumepress Apply
Geometry → Face → Connect/Disconnect Faces → ConnectSelect with the mouse faces aligned between volumes, only this which are atthe cover of small cylinder, see figure 11. This operation is needed to forcecontinuum between volumes. It results in deleting one of the face which arealigned at the same position. After operation two volumes are linked by oneface forcing later the same mesh to be generated for both volumes at that face.Not connected faces will be by default treated as wall. In our case, side cylinderface of the Volume 5 will be a wall.press Apply after making selection
Figure 11: Faces to be selected for Face Connect oparation.
0.2.2 Setting boundary condition types
In order to indicate inlet and outlet of the cyclone we need to specify boundarycondition types in Gambit. Additionally ash hopper has to be marked as sepa-rate wall, this is required for dispersed phase modelling. See listing of boundarytypes setting below.
Zones → Specify Boundary TypesCheck (Add)Enter, Name: inSelect Type VELOCITY INLETPick Entity : Faces, face representing inlet to the cyclone, see Figure 12press Apply
Zones → Specify Boundary TypesCheck (Add)Enter, Name: outSelect Type OUTFLOWPick Entity : Faces, face representing outlet from the cyclone, see Figure 12press Apply
Zones → Specify Boundary TypesCheck (Add)Enter, Name: ashSelect Type WALLPick Entity : Faces, faces creating ash hopper, see Figure 12press Apply
Figure 12: Boundary condition types.
0.2.3 Meshing geometry
Generation of appropriate mesh for cyclone geometry is not a trivial task. Theflow inside a cyclone is fully 3 dimensional and complex. Proper simulation ofsuch flow require careful treatment of the mesh. Since this exercise is only toshow possibilities of Fluent and we rather would like to show general procedureof simulating cyclone operation automatic mesh generator will be used. It isadvised never to use shown here mesh for simulations of real object. See below
procedure for meshing cyclone geometry.
Mesh → FacePick Faces, select all the facesSelect Elements: TriSelect Type: PaveCheck Spacing: ApplyEnter Interval size 0.05Press Apply
Mesh → VolumePick Volumes, select all the volumesSelect Elements: Tet/HybridSelect Type: TgridUncheck Spacing: ApplyPress Apply
Final mesh should contain around 20 000 cells. The last task to perform inGambit is to export generated mesh to the file.File → Export → MeshPress Browse to select destination folder.Enter name of the file, extension will be given by default.Press Accept
0.2.4 Setting Fluent parameters
Herewith procedure of setting up cyclone simulations in Fluent.
Read mesh file (mesh files have extension msh) created in previous section.File → Read → Case...Define solver settings as default.Define → Models → Solver...Set turbulence modellDefine → Models → Viscous...Select k − ε RNG turbulence model with option Swirl Dominated FlowIn the Discrete Phase Model panel change Maximum Number of Steps to 10000Set InjectionsSelect Injection Type → surfaceSelect Release From Surfaces → in (inis an inlet face)Select Material → ashSelect Diameter Distribution → rosin-rammler-logarithmicSelect tab Point PropertiesEnter Total Flow Rate (kg/s) equal to 0.001Enter Min. Diameter (m) equal to 1e-6Enter Max. Diameter (m) equal to 300e-6
Enter Mean Diameter (m) equal to 150e-6Enter Spread Parameter equal to 2.8Enter Number of Diameters equal to 15Select tab Turbulent DispersionFrom Stochastic Tracking select Discrete Random Walk ModelEnter Number of Tries equal to 5Accept settings pressing OKDefine material properties Define → Materials...Change density for airEnter Density (kg/m3) equal to 1.094Confirm changes pressing Change CreateChange density for inert-particle ashEnter Density (kg/m3) equal to 2100Confirm changes pressing Change CreateDefine operating condition Define → Operating Conditions...Select GravityEnter gravitation acceleration Z (m/s2) equal to 9.81Accept settings pressing OKDefine boundary condition Define → Boundary Conditions...Select Zone → in, press SetEnter Velocity Magnitude (m/s) equal to 7.98Select Turbulence Specification Method → Intensity and Hydraulic DiameterEnter Hydraulic Diameter (m) equal to 0.2Accept settings pressing OKSelect Zone → ash, press SetSelect tab DPMUnder Discrete Phase Model Condition select Boundary Cond. Type → trapAccept settings pressing OKSelect Zone → wall, press SetSelect tab DPMUnder Discrete Phase Reflection Condition select Normal → constantEnter value equal to 0.8Under Discrete Phase Reflection Condition select Tangent → constantEnter value equal to 0.8Accept settings pressing OKClose Boundary Condition panelset up solver parameters Solve → Controls → Solution...From Discretization select Momentum → Second Order UpwindFrom Discretization select Turbulent Kinetic Energy → Second Order UpwindFrom Discretization select Turbulent Dissipation Rate → Second Order UpwindAccept settings pressing OKInitialize solution Solve → Initialize→ Initialize...Press Init and close Solution Initialization panelSet solution monitoring option Solve → Monitors → Residual...Under Option select PlotFor Residual → continuity → Convergence Criterion enter value equal to 10e-9
Accept settings pressing OKsave Fluent settings parameter in case file (case files have extension .cas) File→ Write → Case..., enter file name and accept settings pressing OK
0.2.5 Performing calculations
Herewith we assume that Fluent is open and case file with cyclone is read.
Type in Fluent command window it 100, (this command executes 100 iterations)Observe in Fluent result window residuals of the solved equations
Creating planes for extracting calculated variables
Running simulations on 3D domain we do not have direct access to solved vari-able inside the domain. Using Fluent post processing tools we can display onlyvariables on the external boundary of the domain. In order to access variableinside the domain internal lines or planes needs to be created. The best of theflow visualization is to look at variables (velocity, pressure field) on the planeinside the domain. Planes can be placed at arbitral position selected by theuser. From the number of methods of defining planes position available in Flu-ent we suggest to use 3 points method described below. Just in case we donot remember size of the domain geometry and its placement in the cartesiansystem we can display cartesian coordinates on the external boundaries of thedomain geometry (see listing below).
Select Display → Contours...From Option select FilledFrom Contours of select Grid → X-coordinateFrom Surfaces select wallPress DisplayObserve in Fluent result window boundary of the domain colored by X cartesiancoordinateRepeat operation for Contours of → Y-coordinate and Z-coordinate
The cyclone axis is aligned with Z axis and crossing X = 0 and Y = 0 cartesiancoordinates. Now we create plane crossing cyclone for Y = 0.
Select Surface → Plane...From Points enter,x0(m) = 1, x1(m) = 0, x2(m) = 0y0(m) = 0, y1(m) = 0, y2(m) = 0z0(m) = 0, z1(m) = 0, z2(m) = 1(exact coordinates are not important, points can not be aligned, and in our case
all y variables must be equal to 0)
For New Surface Name enter desired name of the surface and press CreateClose Plane Surface panel pressing Close
You can repeat procedure above to create more planes in the arbitral positionsinside analyzed domain. You can see created planes by displaying them in theFluent result window.
Select Display → Grid...Select All from Edge TypeFrom Surface select name of the creates palnePress Display
Displaying Fluent variables on created planes
Fluent provide extremely powerful post processing tool. It allows to display onthe screen all calculated variables and number of predefined derivatives of thesevariables. Here we show general procedure of displaying variables on createdplanes.
Select Display → Contours...From Option select FilledFrom Contours of, select Pressure... → Static PressureFrom Surfaces select plane created in previous stepPress DisplayObserve in Fluent result window plane colored by static pressure field, one cansee that the boundary of the domain are not visible,From Option select Draw Grid panel Grid Display pop upsFrom Edge Type select Feature, and from Surfaces select domain boundary youwant to displayPress Display, now, when displaying contours of variables simultaneously domainboundary wireframe will be displayed
From Contours of, select Velocity... → Velocity MagnitudePress DisplayObserve in Fluent result window plane colored by velocity magnitude field, andthe boundary of the domain
Simulating ash flying inside a cyclone - particle tracking
In most of the cases mass load of the inert particles is small comparing to trans-port gas. If heat transfer between phases in not involved particle can be, withoutconsiderable error, traced within a gas phase in the frame of postprocessing. Itmeans that first we simulate fluid flow of a gas phase. When convergence forcontinues phase is reached inert particle representing ash are traced employing
Lagrangian model. See below for executing tracing procedure.
Select Display → Particle Tracks...From Option activate Draw Grid in order to see boundary of the domain (seesection above for explanation)From Release from Injections select injection-0, (name can be different)Select Track Single Particle Stream, (number of particle traced usually exceed
thousands and tracking procedure in lengthly even on fast computers, in order
to make this faster and be able to see particle paths on the screen we select this
option → particle will be send only from one face at the inlet)Press Display, (Fluent starts tracing procedure, after finishing displays particle
paths in results window.In the main Fluent window report of the tracing procedure is printed. Report
shows how many particles have been traced, trapped, escaped, aborted and in-complete, evaporated for inert particle is meaningless. Trapped are particle col-
lected in the ash hopper. Escaped are these which left the cyclone through the
outlet. Aborted are not traced by the solver due to numerical error.Incompleteare these for which Max. Number of Steps was not enough to complete tracing.See section 0.2.4 for changing Max. Number of Steps for particle tracking.)
Useful option in particle tracking procedure is summary report. It can helpin assessing efficiency of cyclone which is calculated as ratio of the ash massflux collected inside ash hopper to the ash mass flux entering a cyclone. It alsoinforms of the mass flux of incomplete traces. The regular report provide onlythe number of trapped, escaped and incomplete streams which is meaningless inassessing cyclone operation. See procedure below for activating summary report.
Within Particle Trucks panel, select Summary from Report TypeDeselect Track Single Particle StreamPress Track, (particle steams will not be displayed in results window)
See below example of summary report:
number tracked = 3300, escaped = 419, aborted = 0, trapped = 2362, evaporated = 0, incomplete = 519
Fate Number Elapsed Time (s) Injection, Index
Min Max Avg Std Dev Min Max
---- ------ ---------- ---------- ---------- ---------- -------------------- --------------------
Incomplete 519 5.646e-001 4.080e+000 1.130e+000 3.826e-001 injection-0 0 injection-0 515
Trapped - Zone 4 2362 7.418e-001 3.770e+000 1.509e+000 3.425e-001 injection-0 424 injection-0 203
Escaped - Zone 5 419 3.792e-001 3.530e+000 1.003e+000 5.647e-001 injection-0 48 injection-0 275
(*)- Mass Transfer Summary -(*)
Fate Mass Flow (kg/s)
Initial Final Change
---- ---------- ---------- ----------
Incomplete 2.897e-008 2.897e-008 0.000e+000
Trapped - Zone 4 9.996e-004 9.996e-004 0.000e+000
Escaped - Zone 5 3.562e-007 3.562e-007 0.000e+000
The most interesting is Mass Transfer Summary which shows mass fluxes ofIncomplete, Trapped and Escaped particle streams. General report shows onlynumber of incomplete, trapped and escaped particle stream. Sometimes even
large number of escaped particle streams not impose low cyclone efficiency,because these streams could be low diameter particle streams. Hence in orderto asses cyclone efficiency mass fluxes of trapped and escaped particle streamsneeds to be compared. Escaped particle stream number indicate how many traceof the particle streams has not been completed. There are neither trapped norescaped and traced has been finished inside domain. If number and mass fluxof incomplete stream is large we need to increase Max. Number of Steps underDiscrete Phase Model panel opened from Define menu.