Coefficient of restitution for wet particles

TL;DR

This study experimentally investigates how wetting liquids affect the coefficient of restitution for particles bouncing on wet surfaces, highlighting the importance of dimensionless parameters and film thickness in non-lubrication regimes.

Contribution

It provides new insights into the dependence of COR on impact velocity, particle and liquid properties, and introduces the significance of film thickness in non-lubrication regimes.

Findings

COR depends on impact velocity and liquid properties.

Film thickness ratio is crucial in non-lubrication regimes.

Dimensionless numbers characterize the interplay of forces.

Abstract

The influence of a wetting liquid on the coefficient of restitution (COR) is investigated experimentally by tracing freely falling particles bouncing on a wet surface. The dependence of the COR on the impact velocity and various properties of the particle and the wetting liquid is presented and discussed in terms of dimensionless numbers that characterize the interplay between inertial, viscous, and surface forces. In the Reynolds number regime where the lubrication theory does not apply, the ratio of the film thickness to the particle size is found to be a crucial parameter determining the COR.