Acoustic Scattering from Complex Geometries

Abstract

This paper addresses the numerical simulation of the acoustic scattering and propagation through non-uniform mean flows using a high-order, finite-difference, full-conservative Euler solver and, more precisely, the specific problems raised by multi-block structured grids when complex geometries are considered. Two examples of two-dimensional computations of this type are presented. The first case, a benchmark problem from the 4 th CAA Workshop, is the simulation of the acoustic scattering from multiple rigid circular cylinders, without mean flow, of the sound generated by a spatially distributed, axisymmetric source. The proposed solution uses conformal multi-domain grids associating body-fitted grids near solid walls and quasicartesian grids elsewhere. The solutions are favorably compared to analytical data. The second example is the simulation of the acoustic scattering from a high-lift wing section with deployed slat and flap, from a source located in the slat cove region. An acoustic grid is derived from a CFD grid previously used to compute the non-uniform viscous mean flow around the wing. A first acoustic computation, performed with the fluid at rest, is favorably compared to a Boundary Element Method solution. Then a second computation is performed on the non-uniform mean flow. The comparison of both solutions highlights the influence of the flow on the directivity diagram of the sound field.