Computing non-equilibrium turbulent flows with time-dependent rans and vles
The computation of complex non-equilibrium turbulent flows is discussed from a basic theoretical standpoint. An entirely new approach to time-dependent Reynolds-Averaged Navier-Stokes (RANS) computations and Very Large-Eddy Simulations (VLES) is presented. The unique feature of this new approach is that subgrid scale models are proposed that allow a DNS to go continuously to a RANS computation in the coarse mesh/infinite Reynolds number limit. In between these two limits, we have an LES or VLES. Furthermore, the Reynolds stress model that is ultimately recovered in the coarse mesh limit has built in non-equilibrium features that make it suitable for time-dependent RANS. The fundamental technical issues associated with this new approach are discussed in detail and a few illustrative calculations are presented to amplify the central points of the paper.
KeywordsTurbulent Kinetic Energy Reynolds Stress Reynolds Stress Model Subgrid Scale Model Relaxation Time Approximation
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