Multiphysics Model of Lamb Waves Propagation in A Plate Loaded with Droplets

Lamb wave showed the possibilities in ultrasonic inspection technique by analyzing its propagation characteristics, which resulted from the rapid increase in the availability of computing simulation in recent years. These propagation characteristics may be modified to consider the influences of the fluid when plates loaded with liquid droplets. Hence, a coupled plate-droplet system of diffuse-interface was established in this paper, which includes three sub-domains: air, sensor, and plate system. The situation for liquid droplets on the different surface of a single thin plate was compared with the plate without liquid droplets. By calculating a proper separation to locate the transducers on both sides of a thin isotropic plate, the Lamb waves excited from the plate generated its leaky waves into the air domain and the leaky waves detected by the receiver successfully in the simulation. The propagation of Lamb waves and the leaky waves were further visualized by the coupled plate-droplet system based on COMSOL Multiphysics®. The characteristics of Lamb wave propagation differed for the presence of droplets on different surfaces of the plate were discussed by signals analysis. Ultimately, the signals analysis has verified that the received signals were reshaped due to the existence of liquid droplets, and the solution derived with COMSOL Multiphysics® on finite element method led to a thorough understanding of the coupled plate-droplet system and the effect of liquid droplets.