PHOENICS User Meeting 2006 PHOENICS Tomorrow PRELUDE New PHOENICS pre-processor Why does PHOENICS need a new pre- processor? In the first years of PHOENICS,

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PRELUDENew PHOENICS pre-processor

• Why does PHOENICS need a new pre-processor?

• In the first years of PHOENICS, data were input via text files (Q1s) written in PIL (PHOENICS Input Language).

• PIL had (and has) many valuable features: (new-variable declaration, logic, DO loops, CASE structures, file reading, etc; but not all users found it easy.

• Therefore menu-type input procedures were introduced, for users who did not know PIL, so as to write Q1s for them.

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Losses as well as gains

• Much good was done, e.g.-- visual display and manipulation;-- attention focussed on objects.-- use of x, y, z, rather than ix, iy, iz; * But much was lost also, namely:-- declarations,-- logic,-- case structures, etc.This need not have been so, we can now

recognise; but hindsight is easy.

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Resulting shortcomings

• Consequently the Q1 written by the VR-editor defines adequately the data needed for a single solver run.

• However, the Q1 contains no record of the class of runs of which it was a single instance.

• PRELUDE has been introduced as a means of preserving and enriching that record.

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Other motives

• It has also been said that the VR-Editor ‘looks old-fashioned’.

• Perhaps that is because some dialogue boxes are indeed old. Do they betray their Fortran basis?

• PRELUDE does have a more modern appearance; but achieving it has not been a high-priority aim (rightly?).

• More important is that PRELUDE looks (and acts) the same under both Windows and Unix/Linux.

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Relation of PRELUDE to Satellite

• PRELUDE and Satellite work in tandem.

• PRELUDE passes its output to Satellite in the form of a Q1 file, which

• Satellite then converts into eardat and facetdat and passes to the solver for execution.

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PRELUDE as environment

• The activation of Satellite, Solver and Viewer is achieved from within PRELUDE, which thereby acts as an environment.

• It may itself have been activated from the Commander, in its role of 'outer environment'.

• Interactive users of the Satellite can, if they wish, modify the data on its way to the solver, by way of the VR-Editor.

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main features

of PRELUDE, 1

PRELUDE processes input data provided by one or more of the following:

• a single-instance Q1 file, • a multiple-instance Q3 file, • a script containing human-editable

commands, • input, especially of data relationships,

provided interactively by the user. • .dat files defining shapes, • .ac files created by AC3D, • .stl files • .pob files

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main features, 2

• PRELUDE allows relationships to be typed into boxes, whereafter they are acted upon instantly.

• This is probably the most important of all the features of PRELUDE.

• Its relational character distinguishes it from Satellite in the same way as an EXCEL spread-sheet is distinguished from an palm-top calculator.

• Does any competing code possess this?

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Further features

• PRELUDE can launch a series of PHOENICS runs, with different values of specified parameters, and access the results in an orderly way.

• PRELUDE treats 'phi-variables' as objects having attributes, in a manner similar to physical objects (except that they have no visual representation).

• PRELUDE also treats as objects 'models' such as IMMERSOL, k-epsilon, and solid-stress, which appear on the 'object-tree as children of the 'domain' object and as parents of their associated 'phis'.

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Relationships exemplified

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Main features, 3

• PRELUDE can record the results of an interactive-input session in the form of a Q3 file, which, because it preserves the algebraically-expressed relationships between the data elements, can be used for the creation of an unlimited number of individual-instance simulations.

• PRELUDE has 'undo' capabilities.

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Who will use PRELUDE ? 1

• Users of the Gateway approach to PHOENICS (i.e. the ‘goal-scorers’)

• Gateways allow users to perform simulations of pre-defined kinds, with the minimum of difficulty.

• Such users are presented with all that they need, but no more.

• They are not required to make CFD-specific decisions.

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Who will use PRELUDE ? 2

• The makers of Gateways (i.e. mid-field players) usually:

-- consultants, for their clients, -- lecturers, for their students,-- CHAM and CHAM-J staff, for

selected application sectors,-- the company PHOENICS expert,

for his ‘coal-face’ colleagues.

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What is a gateway?

• A Gateway consists of: • a script which sets up an initial scenario; • a 'store-cupboard' containing a set of

objects with attributes which the user is is expected to need ;

• a script embodying a tutorial which enables the new user to learn what to do;

• some exemplary Q3s.

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What is a Q3?

• It is a kind of generalised Q1, embodying classes, of cases, not just single instances.

• It preserves declared variables.• It preserves relationships.• Although often created and

modified interactively, it is human-editable.

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What is a PRELUDE script?

• It is a file written in Tcl/Tk, with extensions introduced by CHAM, which tell PRELUDE what to do.

• It acts like a ‘macro’ of PRELUDE-user key-board entries.

• It is NOT for the general user (either ‘forward’ of ‘mid-field’); but CHAM could offer training in script-writing.

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More about Gateways

• Gateways are much easier to create than special-purpose programs.

• Three which are now being finalised are:

-- The Virtual Wind Tunnel-- Heating, Ventilating and Air-

conditioning-- Fire, and smoke movement.

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PRELUDE demonstrated

G W MichelCHAM

© 2006

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Prelude

• Next generation editor for PHOENICS• Relationships specified mathematically• IN-Form creation of boundary conditions,

buoyancy etc.• More object formats are supported• User writable script extensions• Undo/Redo for most features.• Prompt to save on exit if any parameter

has been changed.

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Relationships

• Parameters are defined as functions of other properties

• Parameters include position, size, rotation of objects, and user variables.

• Checks formulae for type of result (2.4 is not an integer)

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In-Form BCs

• Functions can be specified as functions of coordinates and other parameters

• EG parabolic velocity at inlet with a single inlet object

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As Seen in PRELUDE

• Prelude defines the inform statements as text

• EARTH interprets the statements

• Prelude saves and restores the statements and can add new statements.

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Formats beyond .dat

• Other file formats are supported by the OpenSceneGraph graphics engine.

• EG .3ds model of a watch with texture (it’s about time…)

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Parametric Objects

• Defined using Tcl script (which can be created by the end user or a consultant)

• Example: a baffle with a cutout area. Shape parameters are radius, cutout depth, length and number of facets.

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Parametric Baffle

• Adjusting the parameters such as ‘cutout’ and ‘length’

• changes the shape without editing and saving a geometry file

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Tree Model of Scene

• A Scenegraph is used to optimise performance and achieve hierarchical graphics.

• The table, plus chair and computer is a single assembly but PHOENICS can set separate properties for each component.

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Hierarchical Table

• Rotate the assembly (table) and all the other parts remain at the same relative positions.

• Position in PHOENICS handled automatically by PRELUDE.

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Textured Objects

• Can use ac3d to generate textured objects.

• Or other data sources - here the OSG format sample of a cow….

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Using other objects

• The Cow is passed to EARTH and flow around the cow in a virtual wind tunnel solved.

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Architecture

• Very complex models can be imported into Prelude and exported to EARTH - PARSOL does its best to fit.

• 46982 vertices• 23208 facets

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Results around House

• Very hard to mesh due to open windows, but PARSOL gives this result in less than 4 minutes on a 2GHz PC.

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Multiple runs

• PRELUDE can perform multiple runs, varying a parameter on each run.

• Here an airfoil is placed in the VWT and its incidence changed from -15 to 5 degrees.

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Results of Incidence

• After about 5 minutes CPU, I achieved the 5 runs displayed here. (incidence --15,-10,-5,0,5 degrees)

• The scales of pressure are not identical in the examples.

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Summary

• PRELUDE is the latest tool for access to PHOENICS features

• Users and consultants can produce special purpose ‘gateways’ to enable clients to access the features they need with maximum ease and reliability.

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Future for PRELUDE

• Add a rigid body dynamics code to provide inputs to MOFOR

• Improved access to DWG, DXF or other CAD formats (please tell us your requirements)

• Display of results in the PRELUDE graphics scene.