On the performance of airframe noise prediction on unstructured grids

Airframe noise of complex geometries may conveniently be computed on unstructured grids, which can be generated automatically and quickly. The particular goal of this work is to predict broadband airframe noise of a specific three-element high-lift airfoil configuration on such a grid. Therefore, a discontinuous Galerkin (DG) method provides the spatial discretization of the acoustic perturbation equations, whose turbulent source term is modelled efficiently via the fast random particle-mesh method based on RA NS data. Time integration is carried out by means of the standard, explicit Runge-Kutta scheme of order four (RK4). In two space dimensions, the DG computation on an unstructured triangular grid turned out to be as efficient as a finite difference-based simulationon a sophisticated block-structured grid. Local time stepping significantly increases the performance of the RK4-DG simulation even further. Nevertheless, acoustic results agree well with elaborate scale-resolving approaches.

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