A Modified Pseudopotential Lattice Boltzmann Model With Improved Thermodynamic Consistency for Circular Interface

Abstract The pseudopotential model offers a straightforward solution for multiphase flow. However, it falls short in precisely predicting thermodynamic density and pressure for droplets and bubbles, potentially introducing errors in multiphase flow simulations. This paper introduces a modified pseudopotential lattice Boltzmann method to address the limitation. The model incorporates the equation of state by introducing an external force and modifies the effective mass to ensure thermodynamic consistency, eliminating the need for additional parameters to adjust the equilibrium density of liquid and vapor phases. The model’s performance is validated through benchmark tests and compared with other models. The accurate calculation of the equilibrium density of liquid and vapor for flat interface demonstrates that the model satisfies the thermodynamic consistency. The consistency between surface tension calculated by Young-Laplace law and by an integration across a flat interface is confirmed. The model produces the expected equilibrium thermodynamic pressure for both droplets and bubbles. In addition, the model suppresses spurious velocity by confining its region to near the interface. The features render the model capable in simulating multiphase flow, particularly for scenarios where thermodynamic pressure plays a crucial role.