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APPLICATIONS OF FULLY-RESOLVED LARGE EDDY SIMULATION TO UNSTEADY FLUID FLOW AND AEROACOUSTICS PREDICTIONS

Chisachi Kato
Institute of Industrial Science The University of Tokyo 4-6-1 Komaba, Meguro-ku, Tokyo, 153-8505 Japan

Аннотация

With tremendous speed-up of high-end computers, applications of fully-resolved LES, which directly computes the streamwise vortices in a turbulent boundary layer, will become feasible for engineering flows with a bulk-flow Reynolds number up to several million in about 5 years when the number of computational grids will probably reach 100 billion. A project that is aimed at providing industries with baseline software capable of performing a large-scale engineering LES and acoustical computations are being undertaken. Dynamic Smagorinky Model (DSM) is adopted for LES while Helmholtz equation is solved for the acoustical pressure by using Lighthill's acoustical tensor computed by the incompressible LES. Both solvers are designed such that they are to speed up to one million processing cores, and at this moment their parallel scalability has been confirmed up to 8,192 processing cores in various platforms. Results of extensive validation studies for basic flows show that the fully-resolved LES predicts fluid flow with an expected level of accuracy. In particular, it predicts frequency spectra of the fluctuating velocities and pressure that are almost identical to the measurements. Sound pressure spectra radiated from a small industrial fan was accurately predicted by a combined use of the flow and acoustical solvers.