Large eddy simulation of flow past a circular cylinder with a novel sub-grid scale model

Flow over a circular cylinder is a significant phenomenon encountered in a wide range of engineering and industrial applications. It is a challenging case associated with a complicated flow regime having laminar separation, transition to turbulence, reattachment and vortical motions in the vicinity of cylinder. The current work assesses the performance of RAST (Rahman-Agarwal-Siikonen-Taghinia) model, a zero-equation sub-grid scale (SGS) model in predicting the flow features around a circular cylinder at R-eD = 3900. This SGS model is sensitized to non-equilibrium flows, preserving the anisotropic characteristics of turbulence; this aspect makes it a subtle means to simulate the flow with strong recirculating and separation. Results are compared with available experimental data in the literature as well as with those obtained by the dynamic Smagorinsky model (DSM). The comparisons dictate that the RAST model can accurately produce the mean flow characteristics that are in good agreement with existing experimental data, especially at the near wake of cylinder. Compared with the DSM, the RAST model needs a single-filtering operation that recovers the numerical stability and computational effort to a greater extent. In other words, the RAST model can be considered as a good compromise between accuracy and manageability; particularly, as simple as the original Smagorinsky model and as accurate as the DSM. (C)2015 Elsevier Masson SAS. All rights reserved.