Soumei Baba | Searcharxiv

arXiv2025

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

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.

cond-mat.stat-mech↗

arXiv2023

Generalized equilibria for color-gradient lattice Boltzmann model based on higher-order Hermite polynomials: A simplified implementation with central moments

We propose generalized equilibria of a three-dimensional color-gradient lattice Boltzmann model for two-component two-phase flows using higher-order Hermite polynomials. Although the resulting equilibrium distribution function, which includes a sixth-order term on the velocity, is computationally cumbersome, its equilibrium central moments (CMs) are velocity-independent and have a simplified form. Numerical experiments show that our approach, as in Wen et al. [Phys. Rev. E 100, 023301 (2019)] who consider terms up to third order, improves the Galilean invariance compared to that of the conventional approach. Dynamic problems can be solved with high accuracy at a density ratio of 10; however, the accuracy is still limited to a density ratio of $1\,000$. For lower density ratios, the generalized equilibria benefit from the CM-based multiple-relaxation-time model, especially at very high Reynolds numbers, significantly improving the numerical stability.

physics.comp-ph↗