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Proposed inflow/outflow boundary condition for direct computation of aerodynamic sound. (English) Zbl 0903.76081
Direct simultaneous computation of the flow field and the radiated sound offers the most detailed description of the aerodynamic sound generation processes. The primary difficulty lies in formulating an appropriate numerical boundary condition. This is because domain truncation necessitates the development of nonreflecting boundary conditions. The disparity in amplitudes between the flowfield vorticity, dilatation and the radiating sound field requires extreme accuracy at the boundaries for all angles of incidence. The sound energy may be of an order of magnitude smaller than the flow energy. In cases where high-amplitude nonlinear disturbances must exit the domain with minimal reflection, it has been found necessary to add nonphysical exit zones to the computation of aerodynamic sound. This study proposes a novel zonal approach for the inflow and outflow problems combining the techniques of artificial convection and damping terms. The scheme has been analyzed by using a one-dimensional model equation, and is validated with two model problems. Boundary reflections are significantly reduced compared to the well-known local boundary condition of Thompson.

76Q05 Hydro- and aero-acoustics
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