Tomasz STELMACH. WindSim Annual User Meeting 16 June 2011

Transcription

1 Developments of PHOENICS as CFD engine for WindSim Tomasz STELMACH Ltd, UK WindSim Annual User Meeting 16 June 2011

2 Topics of presentation 1. - who we are, what we do 2. PHOENICS 3. GCV - GENERAL COLOCATED VELOCITY METHOD 4. USP unstructured version of PHOENICS

3 - Concentration Heat And Momentum is a world leading consultancy and software house specialising in computer simulation of fluid-flow, fluid-structure-interaction and heattransfer 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

4 - Concentration Heat And Momentum Software development Model-building and applied consultancy Software sales Introductory/advanced training courses Technical support

5 PHOENICS Aerospace Automotive Chemical Combustion Electronics Cooling Metallurgical Power Generation Turbomachinery Atmospheric flows

6 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

7 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

8 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

9 PHOENICS stand alone programs Virtual Wind tunnel FLAIR Terrain Shell and Tube Heat Exchangers Gas release

10 GCV - GENERAL COLOCATED VELOCITY METHOD

11 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.

12 GCV - GENERAL COLOCATED VELOCITY METHOD Key benefits: Faster convergence, Shorter computational time, Better convergence (results) with complex terrain cases.

13 GCV - GENERAL COLOCATED VELOCITY METHOD Comparison with standard method STANDARD GCV

14 GCV - GENERAL COLOCATED VELOCITY METHOD Computational time: 10 min STANDARD GCV

15 GCV - GENERAL COLOCATED VELOCITY METHOD Terrain simulation example using with GCV=T

16 GCV - GENERAL COLOCATED VELOCITY METHOD Terrain simulation example using with GCV=T

17 GCV - GENERAL COLOCATED VELOCITY METHOD Terrain simulation example using with GCV=T STANDARD GCV

18 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.

19 USP UNSTRUCTURED PHOENICS

20 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)

21 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

22 USP UNSTRUCTURED PHOENICS Example of USP grid

23 USP UNSTRUCTURED PHOENICS COMPARISON SP and USP SP USP

24 USP UNSTRUCTURED PHOENICS COMPARISON SP and USP SP USP USP case converged 6 times faster.

25 USP UNSTRUCTURED PHOENICS USP terrain case example:

26 USP UNSTRUCTURED PHOENICS USP example - results Contours of velocity Contours of pressure

27 USP UNSTRUCTURED PHOENICS USP example convergence plot Converge just after 774 iterations Computational time: aprox. 7min

28 USP UNSTRUCTURED PHOENICS CONCLUSIONS Conclusions: Reduced computation time and memory requirements Results are very similar to standard gird cases Useful for terrain simulation problems

29 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

30 PHOENICS Thank you for attentions! Questions?