Lattice Boltzmann simulations of capillary filling: finite vapour density effects

TL;DR

This paper uses lattice Boltzmann simulations to study capillary filling, revealing that finite vapor density effects can accelerate the front beyond traditional predictions, especially near critical conditions.

Contribution

It demonstrates the impact of finite vapor density on capillary filling dynamics using a pseudo-potential lattice Boltzmann model, highlighting a combined advection and condensation mechanism.

Findings

Front speed exceeds Washburn prediction when vapor density >10% of dense phase.

Finite vapor density causes acceleration of the capillary front.

Potential experimental observation near critical conditions.

Abstract

Numerical simulations of two-dimensional capillary filling using the pseudo-potential lattice Boltzmann model for multiphase fluids are presented, with special emphasis on the role of finite-vapour density effects. It is shown that whenever the density of the light-phase exceeds about ten percent of the dense phase, the front motion proceeds through a combined effect of capillary advection and condensation. As a result, under these conditions, the front proceeds at a higher speed as compared to the Washburn prediction. It is suggested that such an acceleration effect might be observed in experiments performed sufficiently close to critical conditions