Mesoscale Modelling of the Tolman Length in Multi-component Systems

TL;DR

This paper extends the Shan-Chen multi-component Lattice Boltzmann method to analyze curvature effects on surface tension, estimating the Tolman length and higher-order corrections, demonstrating tunable interface properties in mesoscopic models.

Contribution

It introduces a novel application of curvature correction techniques to multi-component systems within the Shan-Chen LBM, including the first estimation of tunable Tolman length in such models.

Findings

Tunable Tolman length observed in asymmetric interactions.

Surface of tension radius calculated via minimization of generalized surface tension.

Higher order curvature and Gaussian-rigidity coefficients estimated.

Abstract

In this paper we analyze the curvature corrections to the surface tension in the context of the Shan-Chen (SC) multi-component Lattice Boltzmann method (LBM). We demonstrate that the same techniques recently applied in the context of the Shan-Chen multi-phase model can be applied to multi-component mixtures. We implement, as a new application, the calculation of the surface of tension radius $R_s$ through the minimization of the generalized surface tension $\sigma[R]$. In turn we are able to estimate the Tolman length, i.e. the first order coefficient of the curvature expansion of the surface tension $\sigma(R)$, as well as the higher order corrections, i.e. the curvature- and the Gaussian-rigidity coefficients. The SC multi-component model allows to model both fully-symmetric as well as asymmetric interactions among the components. By performing an extensive set of simulations we present a first example of tunable Tolman length in the mesoscopic model, being zero for symmetric interactions and different from zero otherwise. This result paves the way for controlling such interface properties which are paramount in presence of thermal fluctuations. All reported results can be independently reproduced through the "idea.deploy" framework available at https://github.com/lullimat/idea.deploy.