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ENERGY TRANSFER OF HYBRID-FILTERED VELOCITY FIELD IN TURBULENT CHANNEL FLOW

Fujihiro Hamba
Institute of Industrial Science, University of Tokyo Komaba, Meguro-ku, Tokyo 153-8505, Japan

Аннотация

Hybrid RANS/LES simulations are expected to accurately predict wall-bounded turbulent flows at high Reynolds numbers. It is known that extra terms due to the non-commutivity between the hybrid filter and the spatial derivative appear in the hybrid-filtered equations. In this work the transport equations for the resolved and modeled energies of the filtered velocity field are investigated using DNS data of turbulent channel flow. In the first case the RANS region is located near the wall for wall modeling in LES. In the second case the RANS and LES regions are located upstream and downstream, respectively. The extra terms show fairly large values in the RANS/LES interface region. It is shown that the extra terms for the convection and the turbulent diffusion represent the energy transfer from the modeled part to the resolved part. These results show that the effect of the extra terms should be taken into account in the filtered Navier-Stokes equation as well as in the turbulent energy equation in hybrid simulations.