Large eddy simulation in complex geometric configurations using boundary body forces

A numerical method is presented that allows large eddy simulation (LES) of turbulent Rows in complex geometric configurations with moving boundaries a nd that retains the advantages of solving the Navier-Stokes equations on fi xed orthogonal grids. The boundary conditions are applied independently of the grid by assigning body forces over surfaces that need not coincide with coordinate lines. The use of orthogonal, nondeforming grids simplifies gri d generation, facilitates the implementation of high-order, nondissipative discretization schemes, and minimizes the spatial and temporal variations i n filter width that complicate unstructured deforming-grid LES, Dynamic sub grid-scale turbulence models are particularly appealing in combination with the body-force procedure because the dynamic model accounts automatically for the presence of solid walls without requiring damping functions. The me thod is validated by simulations of the turbulent Row in a motored axisymme tric piston-cylinder assembly for which detailed experimental measurements are available. Computed mean and rms velocity profiles show very good agree ment with measured ensemble averages. The present numerical code runs on sm all, personal computerlike workstations. For a comparable level of accuracy , computational requirements (memory and CPU time) are at least a factor of 10 lower compared to published simulations for the same configuration obta ined using an unstructured, boundary-fitted deforming-grid approach.