Post on 22-May-2018
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Developments of PHOENICS as CFD engine for WindSim
Tomasz STELMACH CHAM Ltd, UK
ts@cham.co.uk
WindSim Annual User Meeting
16 June 2011
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Topics of presentation
1. CHAM - who we are, what we do
2. PHOENICS
3. GCV - GENERAL COLOCATED VELOCITY METHOD
4. USP – unstructured version of PHOENICS
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CHAM - Concentration Heat And Momentum
CHAM is a world leading consultancy and software house specialising
in computer simulation of fluid-flow, fluid-structure-interaction and heat-
transfer
• Founded by Professor Brian Spalding in 1974
• Independent CFD company run by its founder
• PHOENICS general purpose package
• Specialized, PHOENICS based,
stand alone CFD programs
• CFD engine behind WindSim
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CHAM - Concentration Heat And Momentum
• Software development
• Model-building and applied consultancy
• Software sales
• Introductory/advanced training courses
• Technical support
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PHOENICS
• Aerospace
• Automotive
• Chemical
• Combustion
• Electronics Cooling
• Metallurgical
• Power Generation
• Turbomachinery
• Atmospheric flows
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PHOENICS
Noteworthy Special Features
• RDI: Relational data input allows
parameterization of model scenarios
• In-Form: Input of data via formulae removes
the need for user programming.
• PARSOL: ‘cut-cell’ technique to fit curved
bodies in structured Cartesian grids
eliminates grid-generation problem.
• USP: Unstructured grids are created
automatically
• Parallelisation: domain decomposition
allows simulation of very large scenarios
• PRELUDE: provides user-friendly
application-specific Gateways
• DFW: Distance from wall calculator used in
turbulence and radiation models
• PARAB: Parabolic mode simplifies flows in
ducts, jets and boundary layers
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PHOENICS Usual features
Plus all the usual features:
• 1-,2- and 3-D geometries
• Cartesian, Polar and BFC
• Conjugate Heat Transfer
• Multi-Phase; Particle Tracking
• Chemical reaction; Radiation
• Turbulence
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PHOENICS – terrain related simulations
• flows in rivers and adjacent flood plains;
• flow over and air pollution in urban landscapes;
• the spread of forest fires;
• air and smoke movement in underground passages;
• gas-releases into the atmosphere and consequent explosions;
• thermal and fluid-flow interactions between adjacent equipment items in chemical-industry scenarios
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PHOENICS – stand alone programs
• Virtual Wind tunnel
• FLAIR
• Terrain
• Shell and Tube Heat Exchangers
• Gas release
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GCV - GENERAL COLOCATED
VELOCITY METHOD
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GCV - GENERAL COLOCATED
VELOCITY METHOD
The GCV - alternative algorithm for solving the N-S equations in BFC
geometries.
The main features of the GCV method are:
• A block-structured multi-block implementation, with a capability to tackle
highly non-orthogonal grids. Convergence can be obtained with included
angles as small as 10 degrees.
• A sliding-grid option enables the simulation of problems where a
computational grid is divided into two parts, namely a part which rotates
around the Z axis and a part which is at rest.
•The method uses a segregated pressure-based solver strategy with an
additional correction of cell-centre momentum velocity components, which
converges faster in comparison with the standard one-step face velocity
correction.
• The solver works in a block-by-block manner, but takes the links between
blocks into account implicitly, thus providing fast convergence.
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GCV - GENERAL COLOCATED
VELOCITY METHOD
Key benefits:
• Faster convergence,
• Shorter computational time,
• Better convergence (results) with complex terrain cases.
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GCV - GENERAL COLOCATED
VELOCITY METHOD
Comparison with standard method
STANDARD GCV
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GCV - GENERAL COLOCATED
VELOCITY METHOD
Computational time: 10 min
STANDARD GCV
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GCV - GENERAL COLOCATED
VELOCITY METHOD
Terrain simulation example using with GCV=T
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GCV - GENERAL COLOCATED
VELOCITY METHOD
Terrain simulation example using with GCV=T
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GCV - GENERAL COLOCATED
VELOCITY METHOD
Terrain simulation example using with GCV=T
STANDARD GCV
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GCV - GENERAL COLOCATED
VELOCITY METHOD
Terrain simulation examples using with GCV=T
Conclusions
• Obtain convergence with cases which before it was very
difficult or even impossible,
• Lower computational time,
• Only ~3% increase of memory requirements,
• More reliable results.
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USP – UNSTRUCTURED PHOENICS
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USP – UNSTRUCTURED PHOENICS
• USP is a part of the standard
PHOENICS package, which can
therefore working structured or
unstructured modes at user’s choice.
• All USP grids consist of Cartesian (i.e.) brick-shaped cells.
• USP mesh can be generated automatically via special utility called Automatic Grid Generator (AGG)
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USP – UNSTRUCTURED PHOENICS
Advantages of using USP grids in flow over terrains modelling:
High quality (density) numerical grid is required only in the near ground layer
• For given fineness near the ground, USP uses fewer cells than SP.
• For the same number of cells, USP’s grid is finer near the ground
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USP – UNSTRUCTURED PHOENICS
Example of USP grid
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USP – UNSTRUCTURED PHOENICS
COMPARISON SP and USP
SP USP
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USP – UNSTRUCTURED PHOENICS
COMPARISON SP and USP
SP USP
USP case converged 6 times faster.
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USP – UNSTRUCTURED PHOENICS
USP terrain case example:
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USP – UNSTRUCTURED PHOENICS
USP example - results
Contours of velocity Contours of pressure
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USP – UNSTRUCTURED PHOENICS
USP example – convergence plot
Converge just after 774 iterations
Computational time: aprox. – 7min
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USP – UNSTRUCTURED PHOENICS
CONCLUSIONS
Conclusions:
• Reduced computation time and memory requirements
• Results are very similar to standard gird cases
• Useful for terrain simulation problems
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PHOENICS – near future R&D
• Further development and validation of USP and GCV
solvers
• PARSOL – optimizing for UPS solver
• Optimization for terrain cases
• Introducing parallel processing for USP and GCV
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PHOENICS
Thank you for attentions!
Questions?