Compressible large eddy simulation using unstructured grids: Channel and boundary layer flows

An unstructured grid algorithm for tetrahedral cells has been developed for Large Eddy Simulation (LES). The finite volume form of the compressible Navier-Stokes equations are solved for cell-averaged conservative variables. Inviscid flux computations are performed by applying a Riemann solver across each face, the values at the points on the faces being obtained by least-squares reconstruction from the cell-averaged values. The viscous fluxes and heat transfer are obtained by application of Gauss’ theorem. The numerical scheme is explicit, with second-order spatial and temporal accuracy. The sub-grid scale model is of the constant coefficient Smagorinsky type, with van Driest damping for the viscous sublayer. For channel flow, results at a Reynolds number (based on channel height and bulk velocity) of 5600 and Mach number of 0.5 are compared to incompressible direct numerical simulations (DNS) and experiments. Mean velocity and velocity fluctuations compare well with the DNS and experimental data. For boundary layer flow, results at a Reynolds number (based on the inflow boundary layer thickness) of 20,000 and Mach 3 are compared to experimental data. Preliminary results for profiles of the streamwise mean velocity and turbulence intensity and for the skin friction show good agreement with experiment.