Front pinning in capillary filling of chemically coated channels

TL;DR

This paper investigates how chemically coated boundaries affect capillary filling dynamics, deriving an analytical criterion for front pinning and validating it with numerical simulations.

Contribution

It introduces a new analytical criterion for front pinning in chemically heterogeneous channels and validates it through numerical simulations.

Findings

Analytical criterion accurately predicts front pinning.

Good agreement between theory and Lattice Boltzmann simulations.

Pinning occurs when front interface is much thinner than heterogeneity scale.

Abstract

The dynamics of capillary filling in the presence of chemically coated heterogeneous boundaries is investigated, both theoretically and numerically. In particular, by mapping the equations of front motion onto the dynamics of a dissipative driven oscillator, an analytical criterion for front pinning is derived, under the condition of diluteness of the coating spots. The criterion is tested against two dimensional Lattice Boltzmann simulations, and found to provide satisfactory agreement as long as the width of the front interface remains much thinner than the typical heterogeneity scale of the chemical coating.