A microsphere-surface impact model for implementation in computational fluid dynamics

Two microsphere-surface impact models have been developed for implementation with computational fluid dynamic software. The models consider either normal or oblique incidence of a microsphere with the surface. The first model includes the effects of microsphere-surface roughness, and Hertzian and adhesion damping during surface contact. The second model considers the impact of elastic–plastic sphere and a surface, with and without interface adhesion. Analytical solutions for the coefficients of restitution are presented in terms of the impact velocity and material properties. These algebraic models were validated by comparison with the experimental results of several investigators. A user-defined function representing the model was developed to interface with the commercial software package FLUENT®FLUENT®. The combined modelling package's predictions were compared with high-speed digital images of microparticle contact with the surface located on the floor of a wind tunnel.