# Kinetic Effects in Dynamic Wetting

## TL;DR

This paper develops a kinetic model using the Boltzmann equation to explain how gas effects limit the maximum wetting speed, especially when traditional hydrodynamic models fall short at small scales.

## Contribution

It introduces a novel kinetic model that incorporates gas effects to accurately predict maximum wetting speeds under various conditions.

## Key findings

- Kinetic effects increase maximum wetting speed.
- Reduced gas pressure enhances wetting speed.
- Confinement of the meniscus affects wetting dynamics.

## Abstract

The maximum speed at which a liquid can wet a solid is limited by the need to displace gas lubrication films in front of the moving contact line. The characteristic height of these films is often comparable to the mean free path in the gas so that hydrodynamic models do not adequately describe the flow physics. This Letter develops a model which incorporates kinetic effects in the gas, via the Boltzmann equation, and can predict experimentally-observed increases in the maximum speed of wetting when (a) the liquid's viscosity is varied, (b) the ambient gas pressure is reduced or (c) the meniscus is confined.