Prediction of the effective diffusion coefficient in random porous media using the finite element method
Prediction of the effective diffusion coefficient in random porous media using the finite element method
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DOI：
10.1007/s10934-006-9007-0
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发表时间：
2007-04
影响因子：
2.6
通讯作者：
Deqiang Mu;Zhong‐sheng Liu;Cheng Huang;N. Djilali
中科院分区：
文献类型：
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作者：
Deqiang Mu;Zhong‐sheng Liu;Cheng Huang;N. Djilali
提出了一种基于有限元的多孔固体有效气体扩散系数计算方法。利用该方法，在ANSYS平台下通过参数化程序构建了多孔固体的三维微尺度几何形状；建立了气体有效扩散系数与随机分布多孔固体微观尺度特征之间的关系。结果表明：在随机分布的孔隙介质中，存在一个渗流阈值εp，该渗流阈值随着孔隙网络配位数的增加而减小；当孔隙度ε小于某一值ε l时，有效扩散系数与孔隙度之间呈强烈的非线性关系；对于ε>εL，关系变为拟线性。该分界点ε l随配位数的增加而减小。孔隙网络配位数越大，有效气体扩散系数越高。根据模拟结果和观测结果，提出了有效扩散系数与孔隙率的关系式。
A finite-element-based method is presented for evaluating the effective gas diffusion coefficient of porous solids. Using this method, the 3-D micro-scale geometries of the porous solids are constructed under the ANSYS platform by the parametric code; the relation between effective gas diffusivity and micro-scale features of random-distributed porous solids is established. The results show that in random-distributed pore media, there is a percolation thresholdεp, and this percolation threshold decreases with increasing coordination number of the pore network. The relationship between the effective diffusivity and porosity is strongly nonlinear when the porosity,ε, is less than a certain valueεL; forε>εL, the relationship becomes quasi-linear. This dividing pointεLdecreases with increasing coordination number. The larger the coordination number of the pore network, the higher the effective gas diffusivity. Based on the simulation results and observations, a formula relating the effective diffusion coefficient with porosity is proposed.