Droplets motion on chemically/topographically heterogeneous surfaces

Abstract

We present a numerical study of droplets sliding across chemically heterogeneous surfaces formed by a periodic pattern of alternating hydrophobic and hydrophilic stripes, or topographically heterogeneous surfaces which are microgrooved. The numerical simulation performed by using a particle-based numerical method, Many-body Dissipative Particle Dynamics (MDPD), is adopted to observe the stick-slip motion of droplets driven by a constant body force. The fractions of two types of surfaces are varied from 0.3 to 0.7 to investigate their influence on stick-slip motion of droplets. The dynamic contact angles and the variation in distance Dfr between the front and the rear contact points are shown for different fractions. The jerky motion characterised by stick-slip motion can be found on chemically heterogeneous surfaces for all fractions we choose and the partial stick-slip motion can also be discovered on topographically heterogeneous surfaces except for fraction Φs = 0.3. The snapshots of droplet show that stick-slip motion is the consequence of the periodic deformation of droplet interface during crossing heterogeneous surfaces and can be controlled by fractions.