Hybrid discrete vortex method (DVM)/boundary element method (BEM) calculations for cavity acoustics

A hybrid computational methodology has been developed for cavity acoustics applications. The method utilizes a discrete vortex method coupled to an acoustic boundary element calculation. The discrete vortex method uses a Lagrangian evolution in time and space of a field of Gaussian distributed vortex blobs to simulate a two-dimensional, time-dependent, vorticity dominated shear layer. The method yields accurate and fast unsteady solutions to the time-dependent nonlinear flow equations. The cavity acoustics is modeled using acoustic boundary elements which are distributed on the surface of the cavity geometry. The vortex simulation of the shear layer is coupled to the boundary element calculation through Neumann boundary conditions imposed on the cavity surface. The hybrid method simulates a shear layer interacting with a cavity at low Mach number. In example calculations, acoustic radiation and far-field directivity patterns are calculated for the two-dimensional cavity/shear layer system.