Abstract A wide range of phenomena in natural or engineered systems emerge from strongly coupled hydraulic, chemical and mechanical processes involving a mix of clearly discrete and quasi-continuous mechanisms. Non-local formulations of these processes, e.g. based on Peridynamics, offer significant advantages compared to classical local formulations. Existing Peridynamics models for water flow and chemical transport are applicable only to saturated systems and use loosely coupling schemes, such as explicit time stepping approaches. This work advances the non-local approach by developing a bond-based formulation for coupled water flow and chemical transport in partially saturated porous media. An implicit solution is proposed for coupling the PD formulation of chemical transport with water flow formulation. Firstly, the proposed formulation is verified against results from finite element/finite difference transient solutions for 1-D and 2-D coupled problems. The agreement between results demonstrates the accuracy of the proposed methodology. Secondly, a series of case studies are presented to illustrate the model’s capability to capture discontinuities and heterogeneities, including stationary cracks, propagating cracks, and randomly distributed permeable and impermeable inclusions. The results show that the multi-physics Peridynamics-based formulations and computational model (Pyramid) provide clear advantages to classical local formulations for analyses of reactive transport in partially saturated porous media with physically realistic microstructures.

中文翻译：

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非饱和多孔介质中水流与化学输运耦合的近场动力学建模

摘要 自然或工程系统中的广泛现象来自强耦合的水力、化学和机械过程，涉及明显离散和准连续机制的混合。与经典的局部公式相比，这些过程的非局部公式，例如基于近场动力学，提供了显着的优势。现有的水流和化学传输的近场动力学模型仅适用于饱和系统并使用松散耦合方案，例如显式时间步长方法。这项工作通过开发一种基于键的公式，用于在部分饱和的多孔介质中耦合水流和化学传输，从而推进了非局部方法。提出了一种隐式解决方案，用于将化学传输的 PD 公式与水流公式耦合。首先，针对 1-D 和 2-D 耦合问题的有限元/有限差分瞬态解决方案的结果验证了所提出的公式。结果之间的一致性证明了所提出方法的准确性。其次，提供了一系列案例研究来说明模型捕捉不连续性和非均质性的能力，包括静止裂纹、扩展裂纹以及随机分布的渗透性和非渗透性夹杂物。结果表明，基于多物理场近场动力学的公式和计算模型（金字塔）为分析具有物理现实微观结构的部分饱和多孔介质中的反应输运提供了明显优于经典局部公式的优势。