A thermodynamically consistent free-energy lattice Boltzmann model: Incorporating generalized equilibria derived from the color-gradient approach

Abstract

We extend the chemical-potential-based free-energy lattice Boltzmann (LB) model of Li et al. [Phys. Rev. E 103, 013304 (2021)] by integrating generalized equilibria, originally formulated for the color-gradient LB model using sixth-order Hermite polynomials [Saito et al., Phys Rev E 108, 065305 (2023)], into a thermodynamically consistent framework. Our model is formulated on a three-dimensional D3Q27 lattice with a central-moment collision scheme, simplifying implementation and improving Galilean invariance. Numerical tests, including flat-interface equilibrium, stationary and moving droplets in free space, and wetting on solid surfaces, confirm the model's capability to accurately simulate multiphase phenomena while maintaining strict thermodynamic consistency.