Contact Angle Hysteresis on Randomly Rough Surfaces: A Computational Study

Wetting is important in many applications,
and the solid surfaces
being wet invariably feature some amount of surface roughness. A free
energy-based computational simulation is used to study the effect
of roughness on wetting and especially contact angle hysteresis. On
randomly rough, self-affine surfaces, it is found that hysteresis
depends primarily on the value of the Wenzel roughness parameter r, increasing in proportion with r –
1. Micrometer-level roughness causes hysteresis of a few degrees.