A three-dimensional pseudo-potential-based lattice Boltzmann model for multiphase flows with large density ratio and variable surface tension

• A 3D pseudo-potential-based multiphase LB model is developed.
• The model enables the liquid–gas density ratio to be as large as 700.
• The model allows an independent variation in surface tension and density ratio.

In this paper, we present a three-dimensional pseudo-potential-based lattice Boltzmann (LB) model with an improved forcing scheme for multiphase flows. The Chapman–Enskog multiscale analysis shows that the proposed forcing scheme allows the lattice Boltzmann equation to recover the three-dimensional hydrodynamical equations with additional terms that correspond to the mechanical stability condition and surface tension. Validations of the present LB model with Maxwell construction, Laplace’s law and oscillation dynamics demonstrate that the model enables the density ratio to be as large as 700 in static and quasi-static cases while maintaining variable surface tension. Finally, the application of the model to simulation of the droplet motion in a microchannel shows that the model allows the analysis of important effects, including droplet surface tension, channel surface wettability, and channel surface roughness.