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Application of a parallel rotor CFD code on HPCx

Published online by Cambridge University Press:  03 February 2016

C. B. Allen
Affiliation:
Department of Aerospace Engineering, University of Bristol, Bristol, UK
A. G. Sunderland
Affiliation:
CCLRC Daresbury Laboratory, UK
R. Johnstone
Affiliation:
CCLRC Daresbury Laboratory, UK

Abstract

Aspects of parallel simulation of rotor flows are considered. These flows can be extremely expensive for a compressible finite-volume CFD code, and parallelisation can be essential. The award of HPCx time through the UK Applied Aerodynamics Consortium has allowed large rotor simulations to be performed and wake grid dependence to be investigated. However, there are several issues that need to be investigated when considering very large simulations, including the grid generation process, the parallel flow-solver, including an effective mesh motion approach, and visualisation options. Details of these are presented here, with particular emphasis on the flow-solver parallel performance. A detailed performance analysis of the unsteady flow-solver has been undertaken and the code optimised to improve parallel performance, and details of the parallel scaling performance are presented. The parallel scaling of the code is very good on all the HPC architectures tested here, and this has been recognised by an HPCx Gold Star Capability Incentive award. Results of simulation of a fourbladed lifting rotor in forward flight are also presented, for two mesh densities. It is shown that the solution computed on the serial limit on mesh size, around four million cells, exhibits excessive diffusion, and is of limited use in terms of detailed flow features. The results on a very fine mesh, 32 million cells, have shown a much better solution resolution, and it is also demonstrated that the λ2 vortex core visualisation option is extremely useful.

Type
Research Article
Copyright
Copyright © Royal Aeronautical Society 2007 

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References

1. Bhagwat, M.J. and Leishman, J.G., On the aerodynamic stability of helicopter rotor wakes, May 2000, Proceedings of the 56th Annual AHS Forum, Virginia Beach, VA.Google Scholar
2. Chung, K.H., Na, S.U., Jeon, W.H. and Lee, D.J., A study of rotor tip vortex roll-up phenomenon by using time-marching free-wake method, May 2000, Proceedings of the 56th Annual AHS Forum, Virginia Beach, VA.Google Scholar
3. Brown, R.E., Line, A.J. and Ahlin, G.A., Fuselage and tail-rotor interference effects on helicopter wake development in descending flight, June 2004, Proceedings 60th American Helicopter Society Annual Forum, Baltimore, Maryland.Google Scholar
4. Line, A.J. and Brown, R.E., Efficient high-resolution wake modelling using the vorticity transport equation, June 2004, Proceedings 60th American Helicopter Society Annual Forum, Baltimore, Maryland.Google Scholar
5. Tang, L. and Baeder, J.D., Improved Euler simulation of hovering rotor tip vortices with validation, May 1999, 55th American Helicopter Society Annual Forum, Montreal, Canada.Google Scholar
6. Murayama, M., Nakahashi, K. and Sawada, K., Numerical simulation of vortex breakdown using adaptive grid refinement with vortex-center identification, 2000, AIAA Paper 2000-0806.Google Scholar
7. Steinhoff, J., Wang, C, Underhill, D., Mersch, T. and Wenren, Y., Computational vorticity confinement: a non-diffusive Eulerian method for vortex-dominated flows, 1992, UTSI Preprint.Google Scholar
8. Steinhoff, J. and Underhill, D., Modification of the Euler equations for ‘vorticity confinement’: application to the computation of interacting vortex rings, Physics of Fluids, 1994, 31, pp 27382744.Google Scholar
9. Steinhoff, J., Vorticity confinement: a new techique for computing vortex dominated flows, Frontiers of Computational Fluid Dynamics, 1994, pp 235263, Caughey, D.A. and Hafez, M.M. (Eds), John Wiley and Son.Google Scholar
10. Wang, Cm., Steinhoff, J. and Wenren, Y., Numerical vorticity confinement for vortex-solid body interaction problems, AIAA J, 1995, 33, pp 14471453.Google Scholar
11. Wenren, Y., Fan, M., Dietz, W., Hu, G., Braun, C, Steinhoff, J. and Grossman, B., Efficient Eulerian computation of realistic rotorcraft flows using vorticity confinement. a survey of recent results, 2001, AIAA Paper 2001-2642.Google Scholar
12. Biava, M. and Vigevano, L., Assessment of the vorticity confinement technique applied to rotorcraft flows, 2003, AIAA Paper 2003-3524, Orlando.Google Scholar
13. Slotnick, J.P., Kandula, M., Buning, P.G and Martin, F.W., Numerical simulation of the Space Shuttle launch vehicle flowfield with real gas solid rocket motor plume effects, 1993, AIAA93-0521, 31st Aerospace Sciences Meeting, Reno, NV.Google Scholar
14. Kandula, M. and Buning, P.G., Implementation of LU-SGS algorithm and Roe upwinding scheme in OVERFLOW thin-layer Navier-Stokes code, June 1994, AIAA94-2357, 25th AIAA Fluid Dynamics Conference, Colorado Springs, CO.Google Scholar
15. Ahmad, J. and Duque, E.P.N., Helicopter rotor blade computation in unsteady flows using moving overset grids, J Aircr, 1996, 33, (1), pp 5460.Google Scholar
16. Egolf, T.A., Wake, B.E. and Berezin, C., Recent rotor wake simulation and modelling studies at United Technologies Corporation, 2000, AIAA2000-0115, 38th Aerospace Sciences Meeting, Reno, NV.Google Scholar
17. Wake, B.E. and Choi, D., Investigation of high-order upwinded differencing for vortex convection, AIAA J, 1996, 34, (2), pp 332337.Google Scholar
18. Allen, C.B., Time-stepping and grid effects on convergence of inviscid rotor flows, June 2002, AIAA paper 2002-2817, proceedings 20th Applied Aerodynamics Conference, St Louis.Google Scholar
19. Allen, C.B., Convergence of steady and unsteady inviscid hovering rotor solutions, Int J for Numerical Methods in Fluids, 2003, 41, (9), pp 931949.Google Scholar
20. Gordon, W.J. and Hall, C.A., Construction of curvilinear coordinate systems and applications of mesh generation, Int J of Numerical Methods in Engineering, 1973, 7, pp 461477.Google Scholar
21. Eriksson, L.E., Generation of boundary-conforming grids around wingbody configurations using transfinite interpolation, AIAA J, 1982, 20, (10), pp 13131320.Google Scholar
22. Thompson, J.F., A General three dimensional elliptic grid generation system on a composite block-structure, Computer Methods in Applied Mechanics and Engineering, 1987, 64, pp 377411.Google Scholar
23. Allen, C.B., Chimera volume grid generation within the EROS code, I Mech E. J Aerospace Engineering, 2000, Part G.Google Scholar
24. Allen, C.B., An unsteady multiblock multigrid scheme for lifting forward flight dimulation, Int J for Numerical Methods in Fluids, 2004, 45, (7), pp 973984.Google Scholar
25. Schultz, K.-J., Splettstoesser, W., Junker, B., Wagner, W., Scheoll, E., Arnauld, G., Mercker, E. and Fertis, D., A Parametric wind tunnel test on rotorcraft aerodynamics and aeroacoutics (HELISHAPE) — test documentation and representative results, 1996, 22nd European Rotorcraft Forum, Brighton, UK.Google Scholar
26. Van-Leer, B., Flux-vector splitting for the Euler equations, Lecture Notes in Physics, 1982, 170, pp 507512.Google Scholar
27. Parpia, I.H., Van-Leer flux-vector splitting in moving coordinates, AIAA J, January 1988, 26, pp 113115.Google Scholar
28. Obayashi, S., Freestream capturing for moving coordinates in three dimensions, AIAA J, 1992, 30, (4), pp 11251128.Google Scholar
29. Allen, C.B., Multigrid acceleration of an upwind Euler code for hovering rotor flows, Aeronaut J, September 2001, 105, (1051), pp 517524.Google Scholar
30. Allen, C.B., Multigrid convergence of inviscid fixed-and rotary-wing flows, Int J for Numerical Methods in Fluids, 2002, 39, (2), pp 121140.Google Scholar
31. Jameson, A., Time dependent calculations using multigrid, with applications to unsteady flows past airfoils and wings, AIAA Paper 91-1596.Google Scholar
32. Jameson, A., Transonic flow calculations, 1984, Princeton University, Report MAE 1751.Google Scholar
33. Jameson, A., Time-dependent calculations using multigrid, with applications to unsteady flows past airfoils and wings, 1991, AIAA Paper 91-1596.Google Scholar
34. Thomas, P.D. and Lombard, C.K., Geometric conservation laws and its application to flow computations on moving grid, AIAA J, 1979, 17, (10), pp 10301037.Google Scholar
35. Allen, C.B., Parallel universal approach to mesh motion and application to rotors in forward flight, to appear Int J for Numerical Methods in Engineering.Google Scholar
36. Snir, M., Otto, S., Huss-Lederman, S., Walker, D. and Dongarra, J., MPI: The Complete Reference, 1996, The MIT Press, Cambridge, Massachusetts.Google Scholar
37. HPCx: The UK’s world-class service for world-class research, http://www.hpcx.ac.uk.Google Scholar
38. Central Laboratory of the Research Councils, http://www.cclrc.ac.uk.Google Scholar
39. Edinburgh Parallel Computing Centre, http://epcc.ed.ac.uk.Google Scholar
40. Computer Services for Academic Research, http://www.csar.cfs.ac.uk.Google Scholar
41. Scientific Computing Application Resource for Facilities, http://hpcsg. esc.rl.ac.uk/scarf/groups/index.html.Google Scholar
43. Sunderland, A.G., Emerson, D.R. and Allen, C.B., Parallel performance of a UKAAC helicopter code on HPCx and other large-scale facilities, May 2005, Proceedings 17th International Parallel CFD Conference, Maryland.Google Scholar
44. Gray, A., et al A performance comparison of HPCx Phase 2a to Phase 2, HPCx Technical Report HPCxTR0602, http://www.hpcx.ac.uk/research/hpc/.Google Scholar
46. Singer, B. and Banks, D., A predictor-corrector scheme for vortex identification, 1994, ICASE Report No. 94-11, NASA Langley.Google Scholar
47. Jeong, J. and Hussain, F., On the identification of a vortex, J Fluid Mechanics, 1995, 285, pp 6994.Google Scholar
48. Lin, C-L., Mcwilliams, J.C., Moeng, C-H. and Sullivan, P.P., Coherent structures and dynamics in a neutrally stratified planetary boundary layer flow, Physics of Fluids, 1996, 8, (10), pp 26262639.Google Scholar