Computational Aeroacoustics with Higher Order Methods

The Lighthill acoustic analogy in combination with two different higher-order CFD solvers is used to investigate the sound generation of two test cases. The flow around a cylinder at Re = 150 is analysed with a Discontinous Galerkin method and a counter-rotating open rotor (CROR) with a WENO scheme. The simulation of the cylinder is able to predict both aerodynamic and acoustic behaviour correctly, the vortex street behind the cylinder is responsible for the noise radiation similar to of an acoustic dipole. The analysis of the CROR focuses on the effect of using a higher-order method with a detailed comparison with a standard second order method. While global aerodynamic forces show only small differences, the better transport of vortices, especially of the blade tip vortex, is a benefit for the prediction of interaction noise of the two rotors. This paper includes different investigations on the new HLRS Cray Hermit cluster. The DG code was optimized for single-core usage while still maintaining its good parallel performance. The effect of node-pinning is studied with the CROR configuration which improved the computational time slightly.