Multiple-relaxation-time lattice Boltzmann model for simulating double-diffusive convection in fluid-saturated porous media

TL;DR

This paper introduces a novel multiple-relaxation-time lattice Boltzmann model for accurately simulating double-diffusive convection in porous media, with improved decoupling of thermal and mass diffusivities and validated through numerical tests.

Contribution

The paper develops a new MRT-LB model with modified equilibrium moments and source terms, enhancing simulation accuracy and efficiency for double-diffusive convection in porous media.

Findings

Model accurately simulates double-diffusive convection.

Decouples thermal diffusivity and heat capacity ratio.

Demonstrates efficiency and accuracy through numerical tests.

Abstract

Double-diffusive convection in porous media is a common phenomenon in nature, and has received considerable attention in a wide variety of engineering applications. In this paper, a multiple-relaxation-time (MRT) lattice Boltzmann (LB) model is developed for simulating double-diffusive convection in porous media at the representative elementary volume scale. The MRT-LB model is constructed in the framework of the triple-distribution-function approach: the velocity field, the temperature and concentration fields are solved separately by three different MRT-LB equations. The present model has two distinctive features. First, the equilibrium moments of the temperature and concentration distributions have been modified, which makes the effective thermal diffusivity and heat capacity ratio as well as the effective mass diffusivity and porosity decoupled . This feature is very useful in practical applications. Second, source terms have been added into the MRT-LB equations of the temperature and concentration fields so as to recover the macroscopic temperature and concentration equations. Numerical tests demonstrate that the present model can serve as an accurate and efficient numerical method for simulating double-diffusive convection in porous media.