A numerical study on the coefficient of restitution of wet collisions

TL;DR

This study uses SPH simulations to analyze how the coefficient of restitution in wet collisions depends on fluid and impact parameters, revealing a scaling law and two regimes with different behaviors.

Contribution

It introduces a validated SPH-based numerical approach to identify a scaling law for wet collision restitution, considering effects of Stokes number and film thickness.

Findings

COR depends on Stokes number and film thickness

Two regimes with different power-law exponents are identified

Scaling law governing wet collision behavior is established

Abstract

Using smoothed particle hydrodynamics (SPH) simulations, we investigate the coefficient of restitution (COR) in wet collisions and identify a scaling law governing its behavior. The simulations employ an updated-Lagrangian, mesh-free framework that is validated against experimental measurements. We neglect surface tension effects since the impact conditions correspond to a moderate-to-high Weber number regime. The COR is found to depend on the Stokes number and a dimensionless film thickness defined as the ratio of the liquid film thickness to the diameter of the impacting solid bead. Two distinct regimes are observed, each characterized by different power-law exponents.