Trailing Edge Noise Benchmark Problem: High Fidelity Finite Difference Solutions

Solutions to Category 4, Problem 2 of the Fourth CAA Workshop on Benchmark Problems are obtained using a high order overset grid finite difference scheme. Emphasis is placed on solution quality, including checks of grid and time step convergence, so that the present solutions may be viewed as benchmark quality. Grid convergence of the steady mixing layer solution required for this problem is assessed using the grid convergence index defined by Roach (1998). All solutions, both steady and unsteady, are shown to be temporally and spatially converged on the finest grid considered. The vortex passage problem is found to produce a large initial acoustic transient with high frequency content, which appears to be the most difficult acoustic feature to capture accurately. Both the acoustic pulse problem and the vortex passage problem excite nonlinear shear layer vortices, which lead to late-time hydrodynamic oscillations of the pressure at the near-field acoustic observation point.