Combined Effects of Surface Roughness and Wetting Characteristics on the Moving Contact Line in Microchannel Flows

摘要

The present study investigates moving contact lines innmicrofluidic confinements with rough topographies modeled withnrandom generating functions. Using matched asymptotic expansion, thendescription of the whole contact line is obtained and the dynamic contactnangle is extracted by extrapolating the bulk meniscus to the channel wall.nSignificant variations are observed in the contact angle because of thenheterogeneities of the confining walls of the microfluidic channel. Theneffects of the surface wetting condition also play a crucial role in alteringnthe description of the contact line bearing particular nontrivial interactions with the topological features of the solid boundaries.nIn an effort to assess the underlying consequences, two different surface wetting conditions are studied; namely, complete wettingnsubstrate and partial wetting substrate. Our studies reveal that the consequent wetting characteristics are strongly influenced bynaction of intermolecular forces in presence of surface roughness. The effect of slip, correlation length, and roughness parametersnon the dynamic contact angle have been also investigated.