Impalement transitions in droplets impacting microstructured superhydrophobic surfaces

Department of Physics, University of Jyväskylä - FI-40014 Jyväskylä, Finland, EU

Corresponding author: jari.hyvaluoma@jyu.fi

Received: 7 April 2008
Accepted: 28 July 2008

Abstract

Liquid droplets impacting a superhydrophobic surface decorated with micron-scale posts often bounce off the surface. However, by decreasing the impact velocity, droplets may land on the surface in a fakir state, and by increasing it, posts may impale droplets that are then stuck on the surface. We use a two-phase lattice Boltzmann model to simulate droplet impact on superhydrophobic surfaces, and show that it may result in a fakir state also for reasonable high impact velocities. This happens more easily if the surface is made more hydrophobic or the post height is increased, thereby making the impaled state energetically less favourable.