Multi-Scale Simulation of Near-Wall Turbulent Flows

Abstract

A hybrid two-level large eddy simulation (TLS-LES) is used to study turbulent flow in a converging-diverging channel, which represents a challenging test case due to the appearance of flow separation and subsequent reattachment. While a conventional LES using a localized dynamic subgrid model is employed away from the wall, in the near-wall region a new two-scale approach called the two-level simulation (TLS) approach is employed. A hybrid scale separating operator is used to couple the LES and TLS regimes, and the combined approach that does not contain any ad hoc adjustable parameters is used to simulate high Re wall-bounded flows. The results show that the hybrid TLS-LES approach yields very reasonable predictions of most of the crucial flow features in-spite of using a relatively coarse large-scale grid.