Direct aeroacoustic noise simulations by a high order discontinuous Galerkin method
- Speaker: Prof. Dr. Claus-Dieter Munz
- Place: Seminar room 1.067, Building 20.30
- Time: 11.1.2018, 14:00 - 15:00
- Invited by: CRC 1173
Abstract
One of the key objectives in aeroacoustic optimization is the prevention of tonal noise, which is perceived as most annoying by the observer. Strong tonal noise may occur due to the interaction of acoustic waves with the fluid flow and a resulting feedback. A guiding example in this talk is a side-view mirror of a car, which has been developed in the preliminary design and which was later not usable due to a strong whistling. To capture this phenomenon high fidelity large-scale simulations based on the compressible Navier Stokes equations have been performed resolving acoustic sources and acoustic propagation together with the fluid flow. Due to the large range of spatial, temporal and energetic scales occurring in the acoustic field as well as in the transitional and turbulent flow, this direct approach demands high numerical accuracy while maintaining a certain robustness for the under-resolved flow simulation. We describe the high order discontinuous Galerkin spectral element method used, which exhibits arbitrary high order accuracy as well as excellent scaling for massively parallel simulations. The practical acoustic problem turned out to be quite sensitive with respect to fluctuations in the fluid flow. The whistle frequency switched to different frequencies. This phenomenon is studied for a fluid flow over a cavity. By a non-intrusive method uncertainties are quantified with respect to uncertain flow conditions. Numerical results are shown for cavity problems with different uncertain parameters.