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本文通过数值模拟研究了微孔介质内部结构对气体等效扩散系数的影响。采用随机生成生长方法生成多孔介质的三维微观结构,使用高效的格子-Boltzmann方法求解扩散的控制方程,可预测微孔结构内气体的等效扩散系数。模拟结果表明:微孔材料的内部结构对多孔介质中气体扩散及等效扩散系数有显著影响。对于高孔隙率情况,基于Fick定律数值预测的气体等效扩散系数和实验结果吻合较好;对于部分饱和的颗粒状微孔介质,孔隙内液滴阻碍了气体的扩散路径,多孔介质的无量纲等效扩散系数与饱和度呈非线性关系。
In this paper, the effect of the internal structure of microporous media on the equivalent diffusion coefficient of gas has been investigated by numerical simulation. The three-dimensional microstructure of porous media is generated by random generation growth method. The governing equation of diffusion can be solved by efficient lattice-Boltzmann method, which can predict the equivalent diffusion coefficient of gas in porous structure. The simulation results show that the internal structure of microporous materials has a significant effect on gas diffusion and equivalent diffusion coefficient in porous media. For the case of high porosity, the equivalent diffusion coefficient predicted by Fick’s law coincides well with the experimental results. For partially saturated granular microporous media, the droplet in the pores hinders the gas diffusion path, and the dimensionless porous media Equivalent diffusion coefficient and saturation showed a nonlinear relationship.