Dynamics of Ferrofluid Droplet Impact on Slippery Liquid-Infused Porous Surfaces

In this study, the impact of ferrofluid droplets on slippery liquid-infused porous surfaces (SLIPS) is explored. A model is proposed to take account of the reduction in the initial volume of the ferrofluid droplet caused by the nonuniform external magnetic field. Five modes are identified based on the distinctive postimpact characteristics, and the corresponding phase diagram is summarized. In the low Weber number range (<i>We</i> ≤ 50), the low energy dissipation caused by the low friction characteristics of the SLIPS, combined with the suppression effect of magnetic field on the lateral expansion of the droplet, accumulates the kinetic energy in the vertical direction. Consequently, the bounce height of the ferrofluid droplet on the SLIPS increases with <i>We</i>, which is contrary to that for the superhydrophobic surfaces. The results offer deeper insights into the magnetic controlled droplet rebound and the impact dynamics across diverse surface types.