Viscoelastic wetting transition: beyond lubrication theory

TL;DR

This paper develops a generalized lubrication theory for viscoelastic liquids with normal stresses, extending beyond small contact angles, and analyzes their impact on contact line motion in dip-coating flows.

Contribution

It introduces a new generalized lubrication framework for viscoelastic fluids with normal stresses, applicable to arbitrary contact angles in wetting flows.

Findings

Normal stresses significantly influence contact line dynamics.

The theory extends lubrication models to larger contact angles.

Viscoelastic effects alter advancing and receding contact line behavior.

Abstract

The dip-coating geometry, where a solid plate is withdrawn from or plunged into a liquid pool, offers a prototypical example of wetting flows involving contact-line motion. Such flows are commonly studied using the lubrication approximation approach which is intrinsically limited to small interface slopes and thus small contact angles. Flows for arbitrary contact angles, however, can be studied using a generalized lubrication theory that builds upon viscous corner flow solutions. Here we derive this generalized lubrication theory for viscoelastic liquids that exhibit normal stress effects and are modelled using the second-order fluid model. We apply our theory to advancing and receding contact lines in the dip-coating geometry, highlighting the influence of viscoelastic normal stresses for contact line motion at arbitrary contact angle.