In the conventional representative elementary volume-scale models, details of fluid movement, thermal transfer and mass transport in the porous media are relatively hard to capture, while the understanding of them is crucial in many diverse engineering and environmental applications such as running nuclear power facilities or pollutant diffusion in soil environment. In this paper, a pore-scale lattice Boltzmann method (LBM) modeling of double diffusion systems in saturated porous media is developed to investigate the role played by pore structure in the behavior of salt finger phenomena together with their fluid flow mechanism. An iterative source-correction immersed boundary method is developed to describe the solid skeleton with different boundary conditions for velocity field, heat transfer, and mass transport, respectively. The natural convection in a vertical annulus and the conjugate heat transfer problem in a two-layer horizontal annulus are employed to verify the accuracy and the applicability of the immersed boundary method for Dirichlet-type, Neumann-type and conjugate heat transfer boundary conditions, respectively. Comparisons between the present results and existing investigation show a very good agreement and demonstrate that the double diffusive process in porous media can be predicted with a good accuracy by the proposed model. Subsequently, the instability evolution process of salt finger-type of double diffusive convection in porous media is investigated, with a focus on the structure and behavior of salt fingers and the kinetic energy evolution. The obtained simulation results show that in saturated porous media, relatively large vertical mass fluxes can be generated even if the density distribution is of dynamical stability.

在传统的代表性基本体积尺度模型中，相对难以捕获多孔介质中的流体运动，传热和传质的细节，而对它们的理解在许多不同的工程和环境应用（例如运行核电设施）中至关重要或污染物在土壤环境中的扩散。本文建立了在饱和多孔介质中双扩散系统的孔尺度格子玻尔兹曼方法（LBM）模型，以研究孔结构在盐指现象行为及其流体流动机理中的作用。提出了一种迭代源校正沉浸边界方法，该方法描述了具有不同边界条件的固体骨架，分别用于速度场，传热和质量传递。利用垂直环空自然对流和两层水平环空共轭传热问题分别验证了狄利克雷型，诺伊曼型和共轭传热边界条件的沉浸边界方法的准确性和适用性。 。本研究结果与现有研究之间的比较显示出很好的一致性，并证明了所提出的模型可以很好地预测多孔介质中的双扩散过程。随后，研究了盐指型双扩散对流在多孔介质中的失稳演化过程，重点研究了盐指的结构和行为以及动能演化。获得的模拟结果表明，在饱和多孔介质中，