An advanced direct time domain BEM for 3-D wave propagation in acoustic media

This paper presents a new Boundary Element Method (BEM) in the direct time domain for the solution of the wave propagation problem in 3D homogenous inviscid acoustic media. The methodology is based on impulse response techniques. To this end, the fundamental solutions associated with the Boundary Integral Equation are derived for concentrated sources of higher order B-spline time modulation. High order spatial discretization is adopted. The solution is obtained in two major steps. First the B-spline Impulse Response Functions (BIRF) for a system of a specific geometry are calculated. BIRF functions are independent of the actual external excitation and need to be calculated only once for a given geometry. The second step calculates the response of the system to arbitrary excitations through a mere superposition of the BIRF functions. This paper discusses the development of the proposed BEM methodology and its validation. The method is shown to be stable regardless of the selection of the analysis time step, as opposed to the retarded potential techniques reported in the literature. The high level of accuracy and the efficiency of the method are demonstrated.