Sound shielding simulation by coupled discontinuous Galerkin and fast boundary element methods

A code coupling has been established for performing efficient fan tone shielding simulations of aerial vehicles with unconventional engine installations. In particular, the Fast Multipole Boundary Element Method (FM-BEM) which is formulated to solve a surface integral based on the Kirchhoff-Helmholtz wave equation for large geometries is combined with a volume resolving Discontinuous Galerkin (DG) method which is well suited for the compact region around a jet engine intake where strong mean flow gradients are present. The Mohring-Howe acoustic analogy is utilised during the backward data exchange process for derivation of acoustic velocities in presence of a mean flow. The method can help to overcome a major difficulty related to computational complexity when solving fan noise shilding and scattering problems for a complete aircraft geometry.