Cavity dynamics of water drop impact onto immiscible oil pool with different viscosity

Abstract

In this work, we numerically study the impact of a water droplet onto a deep oil pool. Two fluids are immiscible and the viscosity of the pool liquid is changed systematically. We focus on the cavity dynamics during the impact and especially the effects of the pool liquid viscosity and the impacting velocity. For the parameter range explored, we identify the regime where splashing occurs with corolla breaking into droplets, and the regime where no splashing is observed. Similarity is found for the time evolution of cavity depth for fixed impact velocity and different viscosity, if the cavity depth and time are nondimensionalized by the maximal depth and the time when the maximal depth is reached. Effective power-law scalings are also proposed to describe the dependence of the maximal cavity depth and the corresponding time on the impact velocity and pool liquid viscosity, in the term of Froude and Reynolds numbers.