Large-eddy Simulation Using the Stretched-vortex Sgs Model

Large-eddy simulations of decaying turbulence and turbulent channel ow using the stretched-vortex subgrid-stress model are presented and discussed. In the stretched-vortex model, the subgrid turbulence is assumed to consist of vortices whose orientations are determined by the resolved velocity eld. This, combined with a relationship connecting the subgrid stresses to the vortex-structure orientation and the subgrid kinetic energy, assumed to follow the Kolmogorov form, gives a closed coupling of the SGS model dynamics to the ltered Navier-Stokes equations. The models are not of the eddy-viscosity type. LES calculations using several implementations of the stretched-vortex SGS model are described rst for decaying box turbulence. This is followed by a description of calculations of turbulent ow in an open channel of dimension 4 2 2 at Re = 180. Comparisons with direct numerical simulation are discussed.