(41e) Surface Deformation in a Liquid Environment Resulting from Single-Particle Collisions

Erosion due to collisions has been extensively studied for dry-collisions (gas-particle); however, wet collisions (liquid-particle) belong to a field that has received less attention. The theory of the elastic contact of two bodies developed by Hertz is generally used as a first modeling approximation even in the presence of a liquid. The assumptions of the theory clearly limit its range, depending on the elastic behavior of the materials involved. When "plastic flow" occurs, Hertz theory no longer applies. Furthermore, if the collision occurs immersed in a viscous fluid, the problem will involve the complex interaction between the fluid and the deformation of the solid surfaces. Some of the areas involved are: contact mechanics, adhesion, plasticity, fluid dynamics and thermal effects. This work includes experiments to compare wet-collisions and dry-collisions where plastic deformation is present. Spheres of different diameters and materials collide with a small impact surface, which is attached to a long rod to minimize losses due to elastic waves. The deformation, crater diameter and indentation depth are measured using an optical microscope and a profilometer. Along with these measurements, the impact and rebound velocities are measured. By combining these parameters with the material properties, the research will provide experiments and models on how to quantify the energy loss mechanisms that are involved in particle-wall collisions and define the limits governing those mechanisms.