Aslannejad H, Hassanizadeh S M
1Department of Earth Sciences, Utrecht University, Utrecht, The Netherlands.
2Environmental Hydrogeology Group, Universiteit Utrecht, Princetonplein 9, 3584 Utrecht, The Netherlands.
Transp Porous Media. 2017;120(1):67-81. doi: 10.1007/s11242-017-0909-x. Epub 2017 Aug 3.
In this study, uncoated paper was characterized. Three-dimensional structure of the layer was reconstructed using imaging results of micro-CT scanning with a relatively high resolution . Image analysis provided the pore space of the layer, which was used to determine its porosity and pore size distribution. Representative elementary volume (REV) size was determined by calculating values of porosity and permeability values for varying domain sizes. We found that those values remained unchanged for domain sizes of and larger; this was chosen as the REV size. The determined REV size was verified by determining capillary pressure-saturation imbibition curves for various domain sizes. We studied the directional dependence of curves by simulating water penetration into the layer from various directions. We did not find any significant difference between curves in different directions. We studied the effect of compression of paper on curves. We found that up to 30% compression of the paper layer had very small effect on the curve. Relative permeability as a function of saturation was also calculated. Water penetration into paper was visualized using confocal laser scanning microscopy. Dynamic visualization of water flow in the paper showed that water moves along the fibers first and then fills the pores between them.
在本研究中，对未涂布纸张进行了表征。利用具有相对高分辨率的微型计算机断层扫描（micro-CT）的成像结果重建了该层的三维结构。图像分析提供了该层的孔隙空间，用于确定其孔隙率和孔径分布。通过计算不同区域尺寸下的孔隙率和渗透率值来确定代表性单元体积（REV）尺寸。我们发现，对于尺寸为[具体尺寸]及更大的区域，这些值保持不变；因此选择此尺寸作为REV尺寸。通过确定不同区域尺寸下的毛细管压力-饱和度吸入曲线来验证所确定的REV尺寸。我们通过模拟水从不同方向渗入该层来研究曲线的方向依赖性。我们未发现不同方向的曲线之间存在任何显著差异。我们研究了纸张压缩对曲线的影响。我们发现，纸张层压缩高达30%时对曲线的影响非常小。还计算了作为饱和度函数的相对渗透率。使用共聚焦激光扫描显微镜观察水渗入纸张的情况。对纸张中水流的动态观察表明，水首先沿着纤维移动，然后填充纤维之间的孔隙。
