A lattice Boltzmann model for free-surface flows and wetting processes of generalized Newtonian fluids

Abstract

Free-surface flows and wetting processes of generalized Newtonian fluids are ubiquitous in natural and industrial processes. This paper presents a lattice Boltzmann model integrating a multiple-relaxation-time scheme, a modified mass-exchange interface tracking algorithm, and a height-function approach, verified against analytical solutions and validated by droplet impingement experiments. For power-law fluids, shear-dependent viscosity governs the transient interfacial dynamics, altering splash morphologies during impacts and modifying capillary ascent rates. For Bingham fluids, viscoplasticity acts as an arresting mechanism. A high yield stress can resist inertia and reduce sensitivity to the prescribed equilibrium contact angle, preserving transient deformations and halting interfacial propagation. This work provides a reliable numerical approach for investigating the interfacial evolution of non-Newtonian multiphase systems. • An MRT-LB model for generalized Newtonian fluids (GNFs) free-surface flows and wetting processes is developed. • The model is validated through high-Reynolds-number droplet impingement experiments. • Transient interfacial kinematics governed by power-law rheology are obtained. • Effects of Bingham yield stress on inertia and wettability are revealed.