Large-eddy simulation of a circular cylinder on unstructured grids

Abstract

A computational study of unsteady, separated, low-Reynolds number fluid flow is made using a second-order accurate, cell-centered finite-volume method on unstructured grids. The three-dimensional simulations include large- eddy simulation turbulence modeling using a fixed-coefficient Smagorinsky subgrid-scale model. The flow about a three-dimensional circular cylinder at Reynolds number 3900 and Mach number 0.2 was studied using a standard Navier-Stokes formulation with and without the subgrid-scale modeling. A third case was also tested using a modified form of the Navier-Stokes equations with subgrid-scale modeling. Comparisons are made with experiment and selected three-dimensional numerical calculations performed on structured grids. The frequency of the unsteady vortex shedding was in good agreement with experiment, however, the numerical dissipation inherent in the upwind flux calculations affected the details of the time-averaged flowfield. The results showed an increased base pressure, shortened recirculation zones in the cylinder wake, and excessive drag compared to experiment for all cases.