Chemo-capillary instabilities of a contact line

TL;DR

This paper explores the stability and dynamics of contact lines in fluid systems, highlighting chemo-capillary instabilities and their relation to non-equilibrium phenomena, with implications for understanding complex interfacial behaviors.

Contribution

It introduces a new perspective on contact line behavior by analyzing chemo-capillary instabilities and their differences from classical line tension models in non-equilibrium conditions.

Findings

Contact lines can exhibit fingering, traveling, and oscillatory instabilities.

The relaxation mechanisms of interfacial curvature differ from traditional models.

Instability preferences are significantly affected by non-equilibrium effects.

Abstract

Equilibrium and motion of a contact line are viewed as analogs of phase equilibrium and motion of an interphase boundary. This point of view makes evident the tendency to minimization of the length of the contact line at equilibrium. The concept of line tension is, however, of limited applicability, in view of a qualitatively different relaxation response of the contact line, compared to a two-dimensional curve. Both the analogy and qualitative distinction extend to a non-equilibrium situation arising due to coupling with reversible substrate modification. Under these conditions, the contact line may suffer a variety of chemo-capillary instabilities (fingering, traveling and oscillatory), similar to those of dissipative structures in nonlinear non-equilibrium systems. The preference order of the various instabilities changes, however, significantly due to a different way the interfacial curvature is relaxed.