Process-based characterization of flow in unsaturated fractured rocks

模拟非饱和裂隙岩石中的快速流动仍然是一个挑战，因为存在许多不确定性，包括过程理解、尺度效应和跨尺度的过程参数表征。我们的建议侧重于开发一个模拟工具，用于在局部尺度上模拟非饱和流动，以及评估小尺度过程对大尺度上非饱和裂隙岩石中水的旅行时分布的影响程度。模型开发的主要目的是模拟自由表面流动，包括表面张力和接触线动力学的影响。为此，将开发无网格光滑粒子流体力学(SPH)程序。为了了解裂缝表面发生的流动过程，模拟将涵盖广泛的流动模式和相互作用，范围从(1)毛细管流，(2)裂缝表面的薄层吸附薄膜，和(3)裂缝中的高度非线性流动模式，例如液滴流动。对这些流室之间复杂的水动力相互作用进行建模将大大增强对水在裂隙非饱和岩石材料中传播时间分布的理解，这是普通的体积有效连续介质建模方法如Richards方程所不能捕捉到的。开发的基于颗粒的流动模型将提供一个通用的数值框架，以研究通过各种多孔材料和与固结岩石相关的裂缝几何形状的非饱和流动。

Simulation of rapid flow through unsaturated fractured rocks is still a challenge because of a number of uncertainties ranging from process understanding, scale effects and characterization of process parameters across scales. Our proposal focuses on the development of a modeling tool for simulation of unsaturated flow on a local scale and the assessment in how far small scale processes affect travel time distribution of water in unsaturated fractured rocks on larger scales. The main objective of model development is the simulation of free-surface flow including the effects of surface tension and contact line dynamics. For this purpose, meshless Smoothed Particle Hydrodynamics (SPH) codes will be developed. To obtain an understanding of flow processes that occur on fracture surfaces, simulations will cover a broad spectrum of flow regimes and interactions ranging from: (1) capillary flow, (2) thin adsorbed films on fracture surfaces, and (3) highly non-linear flow regimes in fractures, e.g. droplet flow. Modeling the complex hydrodynamic interplay between these flow compartments will strongly enhance the understanding of travel time distributions of water through fractured unsaturated rock materials, which cannot be captured with common volume effective continuum modeling approaches such as the Richards equation. The developed particle based flow models will provide a versatile numerical framework to investigate unsaturated flow through various porous materials and fracture geometries associated with consolidated rocks.