Peridynamics modelling of coupled water flow and chemical transport in unsaturated porous media
Huaxiang Yan, Majid Sedighi, Andrey P. Jivkov
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.