AI中文摘要
流体和电荷通过多孔材料中不可渗透随机放置颗粒间空隙体积的流动，会在空隙网络在宏观尺度上被破坏的临界浓度处停止。由于空隙区域的不规则形状，这种空隙渗流的临界密度难以计算。我们开发并实现了一种几何精确方法，仅线性缩放于系统体积，用于识别连续空隙的形状和大小。通过这种方式，我们计算了颗粒团簇渗流（随着密度增加，重叠颗粒的系统跨越网络开始出现）和空隙渗流（在更高颗粒浓度下，空隙体积网络不再存在于宏观尺度）的渗流阈值。对于前者和后者，我们计算了柏拉图立体（以及截角二十面体）形状夹杂物在排列和随机取向下的临界浓度。在空隙渗流临界密度的情况下，我们的结果精度相对于先前基准有显著提高。我们还通过考虑立方体形式的不可渗透颗粒，并施加一系列随机放置和取向的断裂面来模拟自然界中发现的剧烈断裂夹杂物，从而引入了夹杂物的结构无序性。随着持续切片数量的增加，我们发现空隙渗流的临界孔隙度趋向于5%。
英文摘要
Fluid and charge flow through interstitial volumes among impermeable randomly placed grains in porous materials ceases to occur at a critical concentration where networks of void volumes are disrupted at macroscopic scales. This critical density for void percolation can be difficult to calculate due to the irregular shape of the void regions. We develop and implement a geometrically exact method, scaling only linearly in the system volume, for identifying the shape and size of contiguous voids. In this manner, we calculate percolation thresholds for both grain cluster percolation (where system spanning networks of overlapping grains begin to appear with increasing density) and void percolation at much higher grain concentrations where networks of interstitial volumes no longer exist on macroscopic scales. For both the former and the latter, we calculate critical concentrations for inclusions in the shape of the Platonic solids (as well as truncated icosahedra) for both aligned and randomly oriented grains. In the case of critical densities for void percolation, the accuracy of our results is significantly improved relative to prior benchmarks. We also incorporate structural disorder of inclusions by considering impermeable grains in the form of cubes subject to a series of randomly placed and oriented fracture planes to mimic aggressively fractured inclusions found in nature. As the number of sustained slices becomes large, we find that the critical porosity for void percolation tends to 5%
