Two-dimensional unstructured elastic model for acoustic pulse scattering at solid-liquid interfaces

A numerical model to simulate elastic waves and acoustic scattering in two spatial dimensions has been developed and thoroughly tested. The model universally includes elastic solids and liquids. The equations of motion are written in terms of stresses, displacements and displacement velocities for control volumes constructed about the nodes of a triangular unstructured grid. The latter conveniently supports various geometries with complex external and internal boundaries separating sub-domains of different elastic properties. Theoretical dispersion for zero mode symmetric (S-0) and antisymmetric (A(0)) waves in a plate has been reproduced numerically with high accuracy, thus verifying the method and code. Comparison of simulated acoustic pulse scattering at water-immersed steel plate with the respective experiments reveals a very good agreement in such delicate features as excitation of the surface (A) wave. The numerical results explain the peculiar location of the surface wave relative to the other ones in experimental registrations. Examples of acoustic pulse interactions with curvilinear metallic shells in water demonstrate flexibility of the method with respect to complex geometries. Potential applications as well as some directions for further improvement to the technique are briefly discussed.