Contact line dynamics in binary lattice Boltzmann simulations

TL;DR

This paper investigates the impact of spurious velocities in single-relaxation-time lattice Boltzmann simulations of binary fluids with different viscosities, and shows how a multiple-relaxation-time approach improves accuracy in contact line dynamics.

Contribution

It identifies the causes of spurious velocities in binary lattice Boltzmann simulations and demonstrates that a multiple-relaxation-time algorithm significantly enhances the accuracy of contact angle predictions.

Findings

Spurious velocities cause errors in equilibrium contact angles.

Multiple-relaxation-time LB method reduces spurious currents.

Contact angle depends on interface velocity during capillary filling.

Abstract

We show that, when a single relaxation time lattice Boltzmann algorithm is used to solve the hydrodynamic equations of a binary fluid for which the two components have different viscosities, strong spurious velocities in the steady state lead to incorrect results for the equilibrium contact angle. We identify the origins of these spurious currents, and demonstrate how the results can be greatly improved by using a lattice Boltzmann method based on a multiple-relaxation-time algorithm. By considering capillary filling we describe the dependence of the advancing contact angle on the interface velocity.