Abstract:

This talk focuses on different numerical methods for simulation of acoustic wave propagation in the areas of architectural acoustics and biomedical ultrasound. For architectural acoustics, the sound field modeling in long spaces is formulated using 1-D transport equations. Experiments obtained from a long room scale model are used to verify the transport equation models. In addition to transport equation models, the use of a diffusion equation to model sound field in various spaces is investigated. Particularly, a modified boundary condition to improve the room-acoustic prediction accuracy of the diffusion equation model is introduced. Simulated and experimental data in a flat room scale model are compared to verify the numerical model. The diffusion equation model is also applied to the study of acoustics in coupled rooms. It will be shown that time-dependent sound energy flows in coupled-room systems experience feedback in cases where the dependent room is more reverberant than the source room. For biomedical ultrasound, two spectral methods (angular spectrum approach and k-space method) are investigated for nonlinear wave propagation based on the Westervelt equation. Spectral methods are superior over conventional FEM and FDTD method due to their low dispersion errors even when the mesh is relatively coarse, therefore is inherently suitable for large-scale biomedical ultrasound propagation. To show the application of the spectral method, the k-space method with a coarse spatial resolution is implemented for the phase correction for transcranial focusing. A sharp focus in the brain is found both in simulation and experiment after the phase correction.
 
 
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