Investigations on the Feature of Turbulent Viscosity Associated with Vortex Shedding

The main purpose of this paper is to investigate the turbulent viscosity, particular its spatial distribution, in the flow around a fixed or moving cylinder. For this purpose, two-dimensional numerical simulations of turbulent flow is performed using the OpenFOAM, in which the Reynolds-averaged Navier-Stokes (RANS) equation, with either k-ɛ or k-ω SST turbulent model, is solved using the finite volume method. The numerical model is validated by using both experimental and numerical results in terms of the mean drag coefficients and the Strouhal number. Turbulent viscosity is significant only in a confined area around the vortex shedding (critical area), and the width of the critical area is considerably affected by the Reynolds numbers (Re) and the motion of the cylinder.