The Boundary Element Method With Finite Differences in Time

This report deals with the formulation and calculation of boundary element methods (BEM) in the time domain. One of the greatest advantages with BEM is that only the boundary of the room has to be discretized instead of the whole enclosed volume. This will usually decrease the calculation time significantly, but the problems with BEM are instead that the integrals on the boundary become more singular, since more information has to be concentrated on a smaller domain (the boundary instead of the volume). This means that the method becomes quite sensitive to numerical evaluation of integrals etc. In this report BEM is formulated and analyzed for acoustic scattering in the time domain, followed by a numerical example that investigates the stability of the method