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Multi-scale Smoothed Particle Hydrodynamics model for flow and transport in unsaturated fractured porous media

非饱和裂隙多孔介质中流动和输运的多尺度平滑粒子流体动力学模型

基本信息

批准号：
320402845
负责人：
Dr. Jannes Kordilla
金额：
--
依托单位：
Abteilung Angewandte Geologie
依托单位国家：
德国
项目类别：
Research Grants
财政年份：
2016
资助国家：
德国
起止时间：
2015-12-31 至 2019-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/320402845?language=en
关键词：
Multi scale Smoothed Particle Hydrodynamics

项目摘要

The main goal of this proposal is the development of a particle-based multi-scale modelling tool to simulate flow and transport dynamics in unsaturated fractures embedded in a porous matrix. The characterization of flow and transport in unsaturated fractured porous media remains one of the most challenging problems in hydrogeology and is of importance for a wide range of applications, such as the quantification of infiltration through thick unsaturated zones of fractured media (nuclear waste repositories), prediction of groundwater recharge and aquifer vulnerability. Flow and transport dynamics in unsaturated fractured porous aquifers are often dominated by a strong heterogeneous geometry and large contrasts in hydraulic properties. Flow dynamics in fractures are difficult to describe quantitatively because of the complex interplay between gravitational, inertial and capillary forces, surface tension, wetting dynamics and the fracture geometry. Small-scale laboratory experiments and numerical models are commonly the only feasible way to capture the highly non-linear flow dynamics and complex interface movements. In particular, strong deforming interfaces pose a challenge to most grid-based modelling approaches, problems that can easily be solved by particle-based models, as particles simply move with the interfaces and/or free surfaces and do not require complex front-tracking schemes. In many cases fractures are embedded in a porous matrix, which does not behave as an impervious medium. The matrix-fracture interface therefore forms an essential connection between the porous matrix, which provides the main storage and the fractures, that acts as the dominating hydraulic pathway through the vadose zone. To model the coupling between these two elements and to simulate the potential feedback mechanisms at the process scale, appropriate modelling approaches are required to reproduce the scale-dependent flow and transport processes. In terms of model discretization it is not feasible to resolve the pore-space and fracture geometry in detail using a single modelling approach as pore throat and fracture apertures are several orders of magnitude apart. Therefore we propose the development of an adapted multi-scale Smoothed Particle Hydrodynamics code. Flow and transport within the porous matrix will be simulated via classical approaches for unsaturated flow such as the Richards equation, which shall be coupled to the discrete free-surface flow dynamics (e.g. adsorbed films, droplets, rivulets) in the fracture. The fully-coupled model will be embedded in a single numerical framework and thus does not require the management of a complex combination of solver routines and coupling methods. The model will be validated by laboratory and numerical experiments and employed to study the effects of the complex free-surface flows and the wetting and transport dynamics at the matrix-fracture interface.

该建议的主要目标是开发一种基于粒子的多尺度建模工具，用于模拟嵌入多孔基质中的非饱和裂缝中的流动和运输动力学。非饱和裂隙多孔介质中的流动和输运特性仍然是水文地质学中最具挑战性的问题之一，并且对于广泛的应用具有重要意义，例如通过裂隙介质（核废物处置库）的厚非饱和区的渗透的量化，地下水补给和含水层脆弱性的预测。非饱和裂隙孔隙含水层中的水流和输运动力学通常由强烈的非均匀几何形状和水力特性的巨大差异所支配。由于重力、惯性力和毛细力、表面张力、润湿动力学和裂缝几何形状之间的复杂相互作用，裂缝中的流动动力学难以定量描述。小规模的实验室实验和数值模型通常是捕捉高度非线性流动动力学和复杂界面运动的唯一可行的方法。特别是，强大的变形接口提出了一个挑战，大多数基于网格的建模方法，可以很容易地解决基于粒子的模型的问题，因为粒子简单地移动的接口和/或自由表面，并不需要复杂的前跟踪计划。在许多情况下，裂缝嵌入在多孔基质中，其不表现为不渗透介质。因此，基质-裂缝界面在多孔基质（提供主要储存）和裂缝（充当通过包气带的主要水力路径）之间形成重要连接。为了模拟这两个元素之间的耦合，并模拟潜在的反馈机制，在过程规模，适当的建模方法，需要重现规模依赖的流动和运输过程。在模型离散化方面，由于孔喉和裂缝孔径相差几个数量级，因此使用单一建模方法详细解析孔隙空间和裂缝几何形状是不可行的。因此，我们建议开发一个适应多尺度光滑粒子流体动力学代码。将通过不饱和流的经典方法（例如理查兹方程）模拟多孔基质内的流动和运输，该方法应与裂缝中的离散自由表面流动动力学（例如吸附膜、液滴、溪流）相耦合。完全耦合的模型将嵌入在一个单一的数值框架，因此不需要管理的求解程序和耦合方法的复杂组合。该模型将通过实验室和数值实验进行验证，并用于研究复杂的自由表面流动和润湿和运输动力学的影响，在基体断裂界面。