DOI QR코드

DOI QR Code

Mesh size refining for a simulation of flow around a generic train model

  • Received : 2016.05.18
  • Accepted : 2016.12.03
  • Published : 2017.03.25

Abstract

By using numerical simulation, vast and detailed information and observation of the physics of flow over a train model can be obtained. However, the accuracy of the numerical results is questionable as it is affected by grid convergence error. This paper describes a systematic method of computational grid refinement for the Unsteady Reynolds Navier-Stokes (URANS) of flow around a generic model of trains using the OpenFOAM software. The sensitivity of the computed flow field on different mesh resolutions is investigated in this paper. This involves solutions on three different grid refinements, namely fine, medium, and coarse grids to investigate the effect of grid dependency. The level of grid independence is evaluated using a form of Richardson extrapolation and Grid Convergence Index (GCI). This is done by comparing the GCI results of various parameters between different levels of mesh resolutions. In this study, monotonic convergence criteria were achieved, indicating that the grid convergence error was progressively reduced. The fine grid resolution's GCI value was less than 1%. The results from a simulation of the finest grid resolution, which includes pressure coefficient, drag coefficient and flow visualization, are presented and compared to previous available data.

Keywords

Acknowledgement

Supported by : Universiti Teknologi Malaysia

References

  1. Alam, F. and Watkins, S. (2006), "Crosswind effects on high cube freight trains", Proceedings of the 3rd BSME-ASME International Conference on Thermal Engineering, Dhaka, Bangladesh.
  2. Ali, M S.M., Doolan, C.J. and Wheatley, V. (2009), "Grid convergence study for a two-dimensional simulation of flow around a square cylinder at low Reynolds number", Proceedings of the 7th International Conference on CFD in the Minerals and Process Industries CSIRO, Melbourne, Australia.
  3. Barton, I.E. (1998), "Comparison of SIMPLE- and PISO-type algorithms for transient flows", Int. J. Numer. Meth. Fl., 26(4), 459-483. https://doi.org/10.1002/(SICI)1097-0363(19980228)26:4<459::AID-FLD645>3.0.CO;2-U
  4. Biadgo, A.M., Simonovic, A., Scorvan, J. and Stupar, S. (2014), "Aerodynamic characteristics of high speed train under turbulent crosswinds", J. Modern Transportation, 22, 225-234. https://doi.org/10.1007/s40534-014-0058-7
  5. Celik, I., Ghia, U., Roache, P.J. and Freitas, C. (2008), "Procedure for estimation and reporting of uncertainty due to discretization in CFD applications", J. Fluid. Eng. -T ASME, 130(7), doi:10.1115/1.2960953.
  6. Chiu, T. (1995), "Prediction of the aerodynamic loads on a railway train in a cross-wind at large yaw angles using an integrated two- and three-dimensional source/vortex panel method", J. Wind Eng. Ind. Aerod., 57(1), 19-39. https://doi.org/10.1016/0167-6105(94)00099-Y
  7. Chiu, T. and Squire, L. (1992), "An experimental study of the flow over a train in a crosswind at large yaw angle up to $90^{\circ}$", J. Wind Eng. Ind. Aerod., 45(1), 47-74. https://doi.org/10.1016/0167-6105(92)90005-U
  8. Gurlek, C., Sahin, B., Ozalp, C. and Akilli, H. (2008), "Flow structures around a three-dimensional rectangular body with ground effect", Wind Struct., 11(5), 345-359. https://doi.org/10.12989/was.2008.11.5.345
  9. Hemida, H. and Baker, C. (2010), "Large-eddy simulation of the flow around a freight wagon subjected to a crosswind", Comput. Fluids, 39(10), 1944-1956. https://doi.org/10.1016/j.compfluid.2010.06.026
  10. Hemida, H. and Krajnovic, S. (2009), "Exploring flow structures around a simplified $30^{\circ}$ side wind using LES", Eng. Appl. Comput. Fluid Mech., 3(1), 28-41.
  11. Hemida, H. and Krajnovic, S. (2010), "LES study of the influence of the nose shape and yaw angles on flow structures around trains", J. Wind Eng. Ind. Aerod., 98(1), 34-46. https://doi.org/10.1016/j.jweia.2009.08.012
  12. Hemida, H., Krajnovic, S. and Davidson, L. (2005), "Large-eddy simulations of the flow around a simplified high speed train under the influence of cross-wind", Proceedings of the 17th AIAA Computational Fluid Dynamics Conference, Toronto, Ontario Canada.
  13. Higuchi, H., Van Langen, P., Sawada, H. and Tinney, C.E. (2006), "Axial flow over a blunt circular cylinder with and without shear layer reattachment", J. Fluids Struct., 22(6-7), 949-959. https://doi.org/10.1016/j.jfluidstructs.2006.04.020
  14. Ishak, I.A., Ali, M.S.M. and Shaikh Salim, S.A.Z. (2016), "Numerical simulation of flow around a simplified high-speed train model using OpenFOAM", Proceedings of the Aerotech VI Conference: Innovation in Aerospace Engineering and Technology, Kuala Lumpur, Malaysia.
  15. Khier, W., Breur, M. and Durst, F. (2000), "Flow structure around trains under side wind conditions: a numerical study", Comput. Fluids, 29(2), 179-195. https://doi.org/10.1016/S0045-7930(99)00008-0
  16. Krajnovic, S. and Davidson, L. (2004), "Large eddy simulation of the flow around an Ahmed body", Proceedings of the ASME Heat Transfer/Fluids Engineering Summer Conference, Charlotte, NC, USA.
  17. Krajnovic, S., Ringqvist, P., Nakade, K. and Basara, B. (2012), "Large eddy simulation of the flow around a simplified train moving through a crosswind flow", J. Wind Eng. Ind. Aerod., 110, 86-99. https://doi.org/10.1016/j.jweia.2012.07.001
  18. Menter, F.M. (1994), "Two-equation eddy-viscosity turbulence models for engineering application", AIAA J., 32(8), 1598-1605. https://doi.org/10.2514/3.12149
  19. Orellano, A. and Schober, M. (2006), "Aerodynamic performance of a typical high-speed train", Proceedings of the 4th WSEAS International Conference on Fluid Mechanics and Aerodynamics, Elounda, Greece.
  20. Osth, J. and Krajnovic, S. (2012), "Simulations of flow around a simplified train model with a drag reducing device using partially averaged navier-stokes", Proceedings of the Conference on Modelling Fluid Flow (CMFF'12). The 15th International Conference on Fluid Flow Technologies, Budapest, Hungary.
  21. Per-Ake, T. (1999), "Experimentell undersokning av sidvindskansligheten hos en model av en tvavaningsbuss I FFA:s vindtunnel LT1", Report (in Swedish) FFA TN 2000-05.
  22. Prime, Z., Moreau, D., Doolan, C.J. and Mat Ali, M.S. (2014), "Flow modelling and noise generation of interacting prisms", Proceedings of the 20th AIAA/CEAS Aeroacoustics Conference, Atlanta, GA.
  23. Rezvani, M.A. and Mohebbi, M. (2014), "Numerical calculations of aerodynamic performance for ATM train at crosswind conditions", Wind Struct., 18(5), 529-548. https://doi.org/10.12989/was.2014.18.5.529
  24. Richardson, L.F. and Gaunt, J.A. (1927), "The deferred approach to the limit. Part I. Single Lattice. Part II. Interpenetrating lattices", Philos. T. Roy. Soc. London. Series A, Containing Papers of a Mathematical or Physical Character, 226, 299-361.
  25. Roache, P.J. (1994), "Perspective: A method for uniform reporting of grid refinement studies", J. Fluid. Eng. -T ASME, 116(3), 405-413.
  26. Robertson, E., Choudhury, V., Bhushan, S. and Walters D.K. (2015), "Validation of OpenFOAM numerical methods and turbulence models for incompressible bluff body flows", Comput. Fluids, 123, 122-145. https://doi.org/10.1016/j.compfluid.2015.09.010
  27. Sakuma, Y. and Ido, A. (2009), "Wind tunnel experiments on reducing separated flow region around front ends of vehicles on meter-gauge railway lines", Aerodynamic Laboratory, Environmental Engineering Division, Japan 50, 20-25. https://doi.org/10.2219/rtriqr.50.20
  28. Stern, F., Wilson, R.V., Coleman, H.W. and Paterson, E.G. (2001), "Comprehensive approach to verification and validation of CFD simulations part 1: Methodology and procedures", J. Fluid. Eng. -T ASME, 123(4), 793-802. https://doi.org/10.1115/1.1412235
  29. Wilcox, D.C. (1993), "Comparison of two-equation turbulence models for boundary layers with pressure gradient", AIAA J., 31(8), 1414-1421. https://doi.org/10.2514/3.11790
  30. Wilcox, D.C. (2006), Turbulence modelling for CFD, 3rd Ed., DCW Industries, Inc.

Cited by

  1. Effect of crosswinds on aerodynamic characteristics around a generic train model 2018, https://doi.org/10.1080/23248378.2018.1424573