Complex Source Distributions in Wave-based Virtual Acoustics

In the typical scenario in time-domain wave-based acoustics, the solution to the acoustic wave equation is approximated over a three-dimensional volumetric grid using a time stepping method. In the setting of very large simulations, the grid is normally assumed to be regular (e.g. Cartesian) so that massive parallelism may be exploited. One difficulty has been in representing source distributions that do not conform neatly to a regular grid. Using a Fourier-based optimisation procedure in the wave vector domain, it is possible to represent arbitrary source distributions in a flexible way over a pre-defined collection of grid points. Such a methodology is independent of the particular choice of simulation method and depends only on the regularity of the grid. In this paper, approximations to various simple distributions, including the line source and piston, are examined, with regard to accuracy, rotation of the distribution relative to the grid, and the size of the point cloud used to represent the source. Numerical results are presented.