# Wetting boundaries for ternary high density ratio Lattice Boltzmann Method

## TL;DR

This paper extends a ternary lattice Boltzmann model to include wetting boundaries, enabling the simulation of complex fluid interactions near solid surfaces with validated accuracy through various tests.

## Contribution

It introduces and compares forcing and geometric schemes for wetting boundaries in a high density ratio ternary lattice Boltzmann model, optimizing implementation for complex multicomponent fluids.

## Key findings

- Dynamic contact angles depend on equilibrium contact angles.
- Slip length varies with interface type and contact angle.
- Model accurately simulates complex ternary fluid dynamics near boundaries.

## Abstract

We extend a recently proposed ternary free energy lattice Boltzmann model with high density contrast, by incorporating wetting boundaries at solid walls. The approaches are based on forcing and geometric schemes, with implementations optimised for ternary (and more generally higher order multicomponent) models. Advantages and disadvantages of each method are addressed by performing both static and dynamic tests, including the capillary filling dynamics of a liquid displacing the gas phase, and the self-propelled motion of a train of drops. Furthermore, we measure dynamic angles and show that the slip length critically depends on the equilibrium value of the contact angles, and whether it belongs to liquid-liquid or liquid-gas interfaces. These results validate the model capabilities of simulating complex ternary fluid dynamic problems near solid boundaries, for example drop impact solid substrates covered by a lubricant layer.