Fluid-acoustic coupling and wave propagation

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This project is focused to the numerical simulation of noise generation and propagation within and in the vicinity of the flow field. This is done in the time domain to enable a close interaction with the computational flow simulation and the physical interpretation with respect to the noise Generation mechanisms. The numerical methods for wave propagation considered are based on the finite-volume (FV) as well as the finite-element (FE) approach and are designed to capture wave propagation with high Resolution An important advantage of these schemes is their straightforward extension to non-Cartesian and non-equidistant grids. But it seems that there are several candidates with better wave propagation properties than the standard finite difference DRPschemes. For the coupling to the flow field two main approaches are considered. For low Mach number flow a perturbation method based on multi-scale asymptotic analysis is investigated from practical and theoretical point of view. These considerations are also extended to low Machnumber flow with heat conduction. Validation and a comparison with other perturbation methods or analogies is perforined with respect to subsonic mixing shear layer and jet flow. For strongly compressible flow a surface coupling of the flow solver with the acoustic solver is perforined. A nonreflecting coupling of the nonlinear and linear mathematical model is established and tested, allowing discontinuous fluxes at the interface.