In this paper, multi-scale modeling was used to resolve diffusion in steam-exploded wood at tracheid scales including sub-micrometer features of bordered pits. Simulations were performed using the lattice Boltzmann method with high-resolution X-ray tomography image data as the input for the microstructure. The results show an effective method for utilizing a variable diffusion coefficient to implement two length scales. This circumvents the need to resolve the bordered pits in detail, which requires massive computing power. Instead, the effective diffusion coefficient for one bordered pit is used as input for this model. Results based on the present model are comparable to experimental data. This methodology can be extended to more structural features at the microscale of wood, such as latewood and the cell wall. Obtaining a map of different diffusion coefficients based on features and scale gives a better overall understanding of diffusion and the importance of mass transport with regard to the pretreatment of wood.

中文翻译：

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蒸汽爆破木材中大分子扩散的多尺度模型

在本文中，多尺度建模用于解决汽爆木材中管胞尺度的扩散问题，包括边缘凹坑的亚微米特征。使用格子 Boltzmann 方法进行模拟，高分辨率 X 射线断层扫描图像数据作为微结构的输入。结果显示了一种利用可变扩散系数实现两个长度尺度的有效方法。这就规避了详细解决边界坑的需要，这需要海量的计算能力。相反，一个边界坑的有效扩散系数用作该模型的输入。基于本模型的结果与实验数据相当。这种方法可以扩展到木材微观尺度的更多结构特征，例如晚材和细胞壁。