Adaptive nonlinear artificial dissipation model for computational aeroacoustics

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Description/Abstract

An adaptive nonlinear artificial dissipation model is presented for performing aeroacoustic computations by high-order and high-resolution numerical schemes based on central finite differences.
It consists of a selective background smoothing term and a well-established nonlinear shock-capturing term, which damps out spuriousoscillations caused by the central differences in the presence of a shock wave and keeps the linear acoustic waves relatively unaffected. A conservative form of the selective background smoothing term is presented to calculate accurate propagation speed or location of the shock wave. The nonlinear shock-capturing term, which has been
modeled by second-order derivative term, is combined with it to improve the resolution of discontinuity and enhance the numerical stability near the shock wave. An adaptive control constant for overall amplitude of the dissipation is automatically calculated according to given grid metrics and time-dependent flow conditions. It is shown that the improved artificial dissipation model reproduces the correct profile and speed of the shock wave, suppresses numerical oscillations near the discontinuity, and avoids unnecessary damping on the smooth linear acoustic waves. The feasibility and performance of the adaptive nonlinear artificial dissipation model for the computational aeroacoustics are investigated and validated by the applications to actual problems.