Large Eddy Simulation with wall functions of Ahmed body

Abstract

Large Eddy Simulation with Wall Function (WFLES) is known to be a cheap alternative to classical LES methods for simulation of flow where large and complex computational meshes are typically required. This makes it attractive for engineering applications. However experience of applying such methods to complex turbulent flows with flow separation and reattachment is still little-known in literature. In this work WFLES of flow around simplified car body with slant angle equal to 25 degrees and ReL = 2.8 · 106 is carried out on Octree mesh to demonstrate the capabilities and limitations of the method in such type of the flow. The results on a series of meshes show that even though the general flow topology is well captured, the critical part of the flow on the slant is hardly predicted even on 100 mln mesh. It is concluded that the prediction of separation above the slant requires significant mesh refinement even in the frame of WFLES.