Flow Past a Backward-Facing Step: Comparison of PANS, DES and URANS Results with Experiments

Flow past a backward-facing step is computed using three different turbulence modeling approaches; Detached Eddy Simulation (DES), Unsteady Reynolds Averaged Navier-Stokes (URANS), and the newly developed Partially Averaged Navier-Stokes (PANS) [1, 2] method. PANS is a family of closure models parameterized by different ratios of resolved-to-modeled kinetic energy and dissipation. The corresponding resolution control parameters are f k (the ratio of unresolved to total kinetic energy) and f ϵ (the ratio of unresolved-to-total dissipation). The main objectives of this study are: (i) to investigate the merits of PANS relative to the other two methods by comparing against existing experimental data; and (ii) to examine the effect of the PANS parameter f ϵ on the computed flow field. In addition, we study the sensitivity of PANS results to grid-size and the level of unsteadiness in the inflow. Overall, the results clearly demonstrate the suitability of PANS for computing unsteady turbulent flows at a reasonable computational expense.

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