3D Finite Element Modeling of Lamb Wave Scattering from a Sessile Water Droplet

The interaction between Lamb waves and a sessile water droplet (i.e., a droplet resting on a horizontal surface) is quite complex and limited research has addressed this issue. However, the similar interaction of Rayleigh waves with a water droplet has been considered, both experimentally and via models. Motivated by these results, this current work applies 3D finite element modeling to study far-field scattering of the fundamental antisymmetric Lamb wave mode from a single, axisymmetric water droplet on an aluminum plate. The profile of the droplet, which is affected by gravity, surface tension, and volume, determines the scattering behavior of incident Lamb waves. For small droplets, the effects of gravity can be ignored and the droplet is well-described by a spherical cap. The effects of the diameter and contact angle of this cap on far-field scattering are investigated by analyzing guided wave signals M the plate with and without the droplet. Scattered wave amplitudes expressed as a function of the scattered angle are compared for a number of different droplet geometries.