Huang Xiang, Zhou Wei, Deng Daxiang
Fujian Key Laboratory of Special Energy Manufacturing, Xiamen Key Laboratory of Digital Vision Measurement, Huaqiao University, Xiamen 361021, China.
Department of Mechanical & Electrical Engineering, Xiamen University, Xiamen 361005, China.
Materials (Basel). 2021 Feb 5;14(4):756. doi: 10.3390/ma14040756.
The understanding of the correlation between a pore-scale structure and its coupled diffusion transport property is crucial in the virtual design and performance optimization of porous fibrous material for various energy applications. Two most common and widely employed pore-scale modeling techniques are the lattice Boltzmann method (LBM) and the pore network modeling (PNM). However, little attention has been paid to the direct comparison between these two methods. To this end, stochastic porous fibrous structures are reconstructed reflecting the structural properties of the fibrous porous material on a statistical level with structural properties obtained from X-ray computed microtomography. Diffusion simulation through the porous phase was subsequently conducted using LBM of D3Q7 lattice and topological equivalent PNM derived from the watershed method, respectively. It is detected that the effective diffusion coefficients between these two methods are in good agreement when the throat radius in the pore network is estimated using the cross-section area equivalent radius. Like most literature, the diffusivity in the in-plane (IP) direction is larger than in the through-plane (TP) direction due to the laid fiber arrangement, but the values are very close. Besides, tortuosity was evaluated from both geometry and transport measurements. Tortuosity values deduced from both methods are in line with the anisotropy of the diffusion coefficients.
理解孔隙尺度结构与其耦合扩散传输特性之间的相关性，对于各种能源应用中多孔纤维材料的虚拟设计和性能优化至关重要。两种最常见且广泛应用的孔隙尺度建模技术是格子玻尔兹曼方法（LBM）和孔隙网络建模（PNM）。然而，这两种方法之间的直接比较却很少受到关注。为此，通过从X射线计算机断层扫描获得的结构特性，在统计层面上重建反映纤维多孔材料结构特性的随机多孔纤维结构。随后分别使用D3Q7格子的LBM和源自分水岭方法的拓扑等效PNM对通过多孔相的扩散进行模拟。当使用横截面积等效半径估计孔隙网络中的喉道半径时，发现这两种方法之间的有效扩散系数吻合良好。与大多数文献一样，由于纤维呈铺设状排列，面内（IP）方向的扩散率大于贯穿平面（TP）方向的扩散率，但两者数值非常接近。此外，还从几何结构和传输测量两方面评估了曲折度。从这两种方法推导出的曲折度值与扩散系数的各向异性一致。
