Numerical simulation of generic side mirror of a car using large eddy simulation with polyhedral meshes

摘要

The flow structure around a generic side mirror of a car is numerically investigated via large eddy simulation (LES) incorporating polyhedral meshes. The aspect ratio defined as height to radius of the cylinder is 3 and the Reynolds number based on cylinder diameter and free stream velocity is 3.2×10{sup}5. The aim of the current paper is not only to show the advantage of the use of polyhedral mesh to model the generic car mirror via LES but also to obtain fluctuating pressure spectra for noise prediction. LES has been an obvious choice for the simulation as it is very suitable for bluff body flows with small effects of boundary layers. It is easier, more flexible and far less time consuming to mesh the current geometry using unstructured mesh rather than a structured conforming mesh. However, central differencing scheme holds better kinetic energy conservation properties on polyhedral cells than on non-conforming tetrahedral cells. Three different grids were tested with local prismatic layer refinements near solid walls. The flow was found to be fully three dimensional with an upstream laminar separation. The stagnation point was located at zero degrees for both the cylinder and the sphere. Pressure spectra were monitored at particular locations upstream of the body and in its wake.