Hybrid RANS-LES method applied to backward facing step flow

作者：Wu Jingfeng^*; Ning Fangfei

来源：Journal of Beijing University of Aeronautics and Astronautics, 2011, 37(6): 701-704.

• Backward facing step
• Backward-facing step flows
• Convective flux
• Delayed-detached eddy simulation
• Detached eddy simulations
• Experimental data
• Flux splitting
• Fourth-order
• Grid-spacings
• Hybrid model
• Hybrid RANS-LES
• Length scale
• Massively separated flow
• Reynolds-Averaged Navier-Stokes
• Skew-symmetric
• Spalart-Allmaras
• Sub-grids
• Subgrid scale models
• Wall distances
• Wall modeling

Turbulent flow over a backward facing step was simulated using a hybrid Reynolds averaged navier stokes (RANS)-large eddy simulation (LES) approach, and the results were compared with experimental data. The hybrid system combines delayed detached-eddy simulation (DDES) with an improved RANS-LES hybrid model aimed at wall modeling in LES (WMLES). It ensures a different response depending on whether the simulation has inflow turbulent content. In the case of with inflow turbulent content, the WMLES branch of the system is active: most of the turbulent is resolved expect the flow near the wall. In the other case, the DDES branch of the system is active, i.e., it gives a pure RANS solution for attached flows and a DES-like solution for massively separated flows. In the system, a scheme which combines the upwind low-diffusion flux-splitting scheme and fourth-order skew-symmetric scheme was used as the convective flux scheme. The spalart-allmaras (S-A) model was applied as a subgrid scale (SGS) model. The definition of the subgrid length-scale was new which depends not only on the grid spacing, but also on the wall distance.

• 出版日期2011
• 单位北京大学