A high-order lattice Boltzmann model for the Cahn-Hilliard equation

TL;DR

This paper introduces a high-order lattice Boltzmann model for the Cahn-Hilliard equation that improves interface tracking accuracy and stability through a redesigned source term and third-order analysis.

Contribution

It presents a novel lattice Boltzmann model with a third-order Chapman-Enskog analysis for better interface simulation in complex flows.

Findings

High accuracy interface tracking demonstrated in simulations

Model maintains stability in complex flow conditions

Source term on diffusive time scale improves interface capture

Abstract

In this paper, a lattice Boltzmann model with the single-relaxation-time model for the Cahn-Hilliard equation (CHE) is proposed. The discrete source term is redesigned through a third-order Chapman-Enskog analysis. By coupling the Navier-Stokes equations, the time-derivative term in the source term is expressed as the relevant spatial derivatives. Furthermore, the source term on the diffusive time scale is also proposed though recovering the macroscopic CHE to third order. The model is tested by simulating diagonal motion of a circular interface, Zalesak's disk rotation, circular interface in a shear flow and a deformation field. It is shown that the proposed method can track the interface with high accuracy and stability. For the complex flow, the source term on the diffusive time scale should be considered for capturing the interface correctly.