A mesoscopic model for microscale hydrodynamics and interfacial phenomena: Slip, films, and contact angle hysteresis

TL;DR

This paper introduces a lattice Boltzmann-based mesoscopic model for simulating dynamic wetting phenomena, capturing interfacial effects like slip, films, and contact angle hysteresis with adjustable parameters.

Contribution

The model uniquely combines a diffuse solid-fluid interface with adjustable disjoining pressure to simulate and control wetting behaviors and hysteresis.

Findings

Able to simulate static and dynamic contact angle hysteresis.

Adjustable slip length for given wettability.

Effective modeling of thin surface films and interfacial phenomena.

Abstract

We present a model based on the lattice Boltzmann equation that is suitable for the simulation of dynamic wetting. The model is capable of exhibiting fundamental interfacial phenomena such as weak adsorption of fluid on the solid substrate and the presence of a thin surface film within which a disjoining pressure acts. Dynamics in this surface film, tightly coupled with hydrodynamics in the fluid bulk, determine macroscopic properties of primary interest: the hydrodynamic slip; the equilibrium contact angle; and the static and dynamic hysteresis of the contact angles. The pseudo- potentials employed for fluid-solid interactions are composed of a repulsive core and an attractive tail that can be independently adjusted. This enables effective modification of the functional form of the disjoining pressure so that one can vary the static and dynamic hysteresis on surfaces that exhibit the same equilibrium contact angle. The modeled solid-fluid interface is diffuse, represented by a wall probability function which ultimately controls the momentum exchange between solid and fluid phases. This approach allows us to effectively vary the slip length for a given wettability (i.e. the static contact angle) of the solid substrate.