In order to determine the soil–water retention (SWR) behavior of a particulate medium, the invading phase pressure in the inter-particle level is correlated to the governing effective pore area in the wetting and drying paths. In a three-phase medium that consists of air, wetting fluid and solids, the invading phase on the drying path is air, whereas on the wetting path the wetting fluid advances into the cavities. On a drying path where the area of a cavity is minimum, the air-entry pressure (AEP) of a pore throat is determined by numerically solving the Young–Laplace curvature equation. This can be done using the finite difference method and Newton–Raphson (Jacobian) approximation technique. Next, a relation between the pore area and the value of AEP is developed by varying the distance between solids around the pore throat. Similarly, the water-entry pressure (WEP) is correlated to a maximum pore area of cavity. After packing the particulate domain with the given particle size distribution (PSD) and void ratio values, the primary/main drying and wetting paths of the wetting fluid are simulated and the effect of hysteresis in SWR is shown. It is considered that the total suction equals to matric suction value and the water bridges between two adjacent particles are formed in the form of pendular rings. In this study, the considered material is non-plastic and the shrinkage and swelling during the drying and wetting phases or any change in pore structure are neglected. The simulation results are compared to experimentally determined as well as estimated data from the literature and a great agreement between the results is found, which offers a reliable way around conducting tedious and expensive SWR tests.

中文翻译：

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模拟土壤水滞留中的滞后现象，以及侵入压力与有效有效流动面积之间的关系

为了确定颗粒介质的土壤水分保持（SWR）行为，颗粒间水平的侵入相压力与润湿和干燥路径中控制有效孔隙面积相关。在由空气，润湿液和固体组成的三相介质中，干燥路径上的侵入相是空气，而在润湿路径上，润湿液则进入空腔。在腔体面积最小的干燥路径上，通过数值求解Young-Laplace曲率方程式来确定孔喉的进气压力（AEP）。可以使用有限差分法和Newton-Raphson（Jacobian）逼近技术来完成。接下来，通过改变孔喉周围的固体之间的距离来开发孔面积与AEP值之间的关系。同样，水进入压力（WEP）与空腔的最大孔面积相关。用给定的粒度分布（PSD）和空隙率值填充颗粒域后，模拟了润湿液的主要/主要干燥和润湿路径，并显示了SWR中的滞后效应。认为总吸力等于矩阵吸力值，并且两个相邻颗粒之间的水桥以摆环的形式形成。在这项研究中，考虑的材料是非塑料的，在干燥和润湿阶段的收缩和溶胀或孔结构的任何变化都被忽略了。将模拟结果与实验确定的结果以及文献中的估计数据进行比较，结果之间存在很大的一致性，