Shape of a sliding capillary contact

TL;DR

This paper investigates how the shape of a capillary contact area between a parabolic body and a plane changes under slow tangential movement, considering contact angle hysteresis and different friction laws.

Contribution

It introduces a theoretical analysis of the contact area's shape evolution under different boundary friction assumptions during slow sliding.

Findings

Contact area remains circular in equilibrium.

Shape deformation depends on the friction law applied.

Hysteresis effects influence the contact boundary shape.

Abstract

We consider a classical problem of a capillary neck between a parabolic body and a plane with a small amount of liquid in between. In the state of thermodynamic equilibrium, the contact area between the bodies and the liquid layer has a circular shape. However, if the bodies are forced to slowly move in the tangential direction, the shape will change due to the hysteresis of the contact angle. We discuss the form of the contact area under two limiting assumptions about the friction law in the boundary line.