Viscous Flow Over a Chemically Patterned Surface

TL;DR

This paper demonstrates how wettability variations on a solid surface influence viscous flow, challenging classical no-slip assumptions, using interface formation theory to describe the effects in a continuum framework.

Contribution

It introduces a continuum model incorporating interface formation theory to account for wettability effects on viscous flow over chemically patterned surfaces.

Findings

Flow disturbance proportional to difference in contact angles

Wettability impacts flow even on flat surfaces

Results align with experimental and molecular dynamics observations

Abstract

The classical fluid dynamics boundary condition of no-slip suggests that variation in the wettability of a solid should not affect the flow of an adjacent liquid. However experiments and molecular dynamics simulations indicate that this is not the case. In this paper we show how flow over a solid substrate with variations of wettability can be described in a continuum framework using the interface formation theory developed earlier. Results demonstrate that a shear flow over a perfectly flat solid surface is disturbed by a change in its wettability, i.e. by a change in the chemistry of the solid substrate. The magnitude of the effect is shown to be proportional to cos(t1)-cos(t2) where t1 and t2 are the equilibrium contact angles that a liquid-gas free surface would form with the two chemically different parts of the solid surface.