Dynamics of two-dimensional liquid bridges

TL;DR

This paper uses lattice Boltzmann simulations to analyze the shape, deformation, and breakup conditions of two-dimensional liquid bridges between solid substrates, considering effects of wettability, gravity, and motion.

Contribution

It introduces a multicomponent pseudopotential lattice Boltzmann method to study dynamic liquid bridges, including deformation and breakup, validated against analytical equilibrium shapes.

Findings

Drag force varies with velocity, contact angle, and Bond number.

Bridge deformation depends on contact angle changes during motion.

Critical velocity for breakup depends on initial contact angles and Bond numbers.

Abstract

We have simulated the motion of a single vertical, two-dimensional liquid bridge spanning the gap between two flat, horizontal solid substrates of given wettabilities, using a multicomponent pseudopotential lattice Boltzmann method. For this simple geometry, the Young-Laplace equation can be solved (quasi-)analytically to yield the equilibrium bridge shape under gravity, which provides a check on the validity of the numerical method. In steady-state conditions, we calculate the drag force exerted by the moving bridge on the confining substrates as a function of its velocity, for different contact angles and Bond numbers. We also study how the bridge deforms as it moves, as parametrized by the changes in the advancing and receding contact angles at the substrates relative to their equilibrium values. Finally, starting from a bridge within the range of contact angles and Bond numbers in which it can exist at equilibrium, we investigate how fast it must move in order to break up.