LES of transitional flows using the approximate deconvolution model

摘要

Large-eddy simulations of transitional incompressible channel flow on rather coarse grids are performed. The standard approximate deconvolution model (ADM) as well as two modifications are compared to fully resolved direct numerical simulation (DNS) calculations. The results demonstrate that it is well possible to simulate transitional flows on the basis of ADM. During the initial phase of transition, the models remain inactive and do not disturb the flow development as long as it is still sufficiently resolved on the coarse large-eddy simulation (LES) grid. During the later stages of transition the model contributions provide necessary additional dissipation. Due to the dynamic determination of the model coefficient also employed for the standard ADM, no ad hoc constants or adjustments are needed. The results of the modified ADM show excellent agreement with DNS already on coarser meshes than the standard ADM, e.g. in the skin friction throughout the transitional phase, while preserving the accuracy for the fully developed turbulent channel flow. A grid-resolution study demonstrates convergence of LES to the DNS results. Results of the dynamic Smagorinsky model are included for comparison.