Interface Source Terms for High-Order Aeroacoustics

摘要

This paper presents two novel techniques to introduce source terms in the linearized Euler equations for the simulation of aeroacoustic propagation on a background mean flow. The first technique allows introduction of a prescribed disturbance in the computational domain through the use of source terms in the numerical flux of the discontinuous Galerkin method instead of volume or boundary sources. With this technique, it is possible to generate entropy hotspots, vortices, and acoustic waves in an accurate manner without generating spurious waves. The second technique introduces a wave-packet source with a band-limited spectrum to obtain, in one single time-domain calculation, the frequency response of the acoustic field over a wide range of frequencies. The formulation of the wave-packet signal and its implementation as an interface duct-mode source are described together with the postprocessing procedure required to obtain accurate results. Validation examples are given for the radiation of sound from a semi-infinite duct with flow.