Acoustic wave propagation: 2D Wigner and 3D wavefront simulations

Abstract

Recently, we have applied an angular-spectrum based method, the thin-element decomposition (TED), to calculate SAW propagation in waveguide structures. However, the angular spectrum does not allow for reflections in the waveguide, which leads to discrepancies for long strips. This has lead us to use the Wigner-distribution function to describe the propagation of SAW in the paraxial limit. This approach leads to a ray-tracing type algorithm which is fast and easy to implement. We calculate wave propagation in a waveguide and compare the results to those given by the classical guided mode theory. We also discus the behaviour of Wigner distribution functions near sharp boundaries. We have also simulated expanding acoustic wavefronts produced by a point disturbance in a bulk. Due to elastic anisotropy of the solid, the energy flux associated with a plane wave is not collinear with the wave vector and, correspondingly, wave fronts (which correspond to the group-velocity surfaces) are not spherical.