Energy-Based Boundary Element Method for High-Frequency Broadband Sound Fields in Enclosures

Abstract

This work sets forth a new method for predicting the spatialvariation of mean square pressure within two-dimensional enclosures containing high-frequency broadband sound fieldsand light to moderate absorption. In the new method, theenclosure boundaries are replaced by a continuous distribution of broadband uncorrelated sources, each ofwhich provides a constituent field expressed in terms ofmean square pressure and time average intensity variables. Superposition of these fields leads to the overall mean square pressure and time average intensity as a function ofposition. Boundary conditions for radiating and absorbing surfaces are recast in terms of energy and intensityvariables. The approach is implemented as a boundaryelement formulation for efficient evaluation of the pressureand intensity fields in enclosures. In contrast totraditional boundary element methods, the new method isindependent of frequency. A two-dimensional model problemenclosure is investigated to verify the new method. The exact analytical solution for the mean square pressuredistribution within the model problem enclosure is obtainedand compared to the results predicted by the new method.The comparisons indicate that the new method is asignificant improvement upon classical diffuse field theoryand computationally efficient relative to traditional boundary element methods and ray tracing techniques.