VS2DRTI: Simulating Heat and Reactive Solute Transport in Variably Saturated Porous Media

Abstract

Variably saturated groundwater flow, heat transport, and solute transport are important processes in environmental phenomena, such as the natural evolution of water chemistry of aquifers and streams, the storage of radioactive waste in a geologic repository, the contamination of water resources from acid-rock drainage, and the geologic sequestration of carbon dioxide. Up to now, our ability to simulate these processes simultaneously with fully coupled reactive transport models has been limited to complex and often difficult-to-use models. To address the need for a simple and easy-to-use model, the VS2DRTI software package has been developed for simulating water flow, heat transport, and reactive solute transport through variably saturated porous media. The underlying numerical model, VS2DRT, was created by coupling the flow and transport capabilities of the VS2DT and VS2DH models with the equilibrium and kinetic reaction capabilities of PhreeqcRM. Flow capabilities include two-dimensional, constant-density, variably saturated flow; transport capabilities include both heat and multicomponent solute transport; and the reaction capabilities are a complete implementation of geochemical reactions of PHREEQC. The graphical user interface includes a preprocessor for building simulations and a postprocessor for visual display of simulation results. To demonstrate the simulation of multiple processes, the model is applied to a hypothetical example of injection of heated waste water to an aquifer with temperature-dependent cation exchange. VS2DRTI is freely available public domain software.

muFlowReacT: A Library to Solve Multiphase Multicomponent Reactive Transport on Unstructured Meshes

“…Since 2015, the U.S. Geological Survey provides an API (PhreeqcRM) of the stand‐alone PHREEQC version (Parkhurst and Appelo 2013). The API substantially simplifies the integration of its components into other codes (Parkhurst and Wissmeier 2015) and several coupled codes that employ PhreeqcRM have been developed and presented since then (e.g., Healy et al 2018; Muniruzzaman and Rolle 2019). In muRT, the Phreeqc API has been included as an OpenFoam class that can be called whenever required.…”

“…Perhaps most significantly, the library does not allow to simulate unconfined groundwater flow systems, which is a severe limitation. In order to equip OpenFoam with suitable geochemical reaction capabilities, we followed the path of earlier coupling efforts in applying a sequential operator splitting approach (e.g., Walter et al 1994; Jacques et al 2012) and employed the USGS code PHREEQC as reaction simulator (e.g., Appelo and Willemsen 1987; Prommer et al 2003; Parkhurst et al 2010; De Sousa 2012; Healy et al 2018; Muniruzzaman and Rolle 2019; Lu et al 2022). Indeed, the popularity of coupling PHREEQC to flow/solute transport simulators has triggered the USGS to develop and release the PhreeqcRM API (available under GNU license), aimed at simplifying the mechanics of model coupling (Parkhurst and Wissmeier 2015).…”

Impact of diffuse layer processes on contaminant forward and back diffusion in heterogeneous sandy-clayey domains

“…In contrast, the multicomponent ionic transport in the free water and diffuse layer porosities is solved with a finite volume method in streamline-oriented grids following the approach of Cirpka et al (1999a,b). Furthermore, MMIT-Clay uses PHREEQC (Parkhurst and Appelo, 2013) as a reaction engine, utilizing the PhreeqcRM module (Parkhurst and Wissmeier, 2015), to allow flexibility to include all the chemical reactions that can be handled with PHREEQC (e.g., Jara et al 2017;Healy et al, 2018;Rolle et al 2018;Sprocati et al 2019;. Further details regarding numerical methods, implementation and solution approaches, and the verification of the code are available in Muniruzzaman and Rolle (2019).…”

Multicomponent Ionic Transport Modeling in Physically and Electrostatically Heterogeneous Porous Media With PhreeqcRM Coupling for Geochemical Reactions

“…Furthermore, the presented multicomponent ionic transport code (MMIT-Clay) is coupled with PHREEQC (Parkhurst & Appelo, 2013), taking advantage of the capabilities of linking this geochemical simulator with transport codes (Charlton & Parkhurst, 2011;He et al, 2015;Nardi et al, 2014;Parkhurst & Wissmeier, 2015;Wissmeier & Barry, 2011;Muniruzzaman & Rolle, 2016). MMIT-Clay utilizes the PhreeqcRM module (Parkhurst & Wissmeier, 2015), which allows great flexibility and a multipurpose framework to access all the PHREEQC's reaction capabilities (e.g., Healy et al, 2018;Jara et al, 2017;Rolle et al, 2018). At the end of the advective and dispersive transport within a time step (Δt), the concentration vector of all the species (primary and secondary species from aqueous speciation) is passed to PhreeqcRM to perform reaction calculations (i.e., any other reactions excluding Donnan and/or interlayer processes), which are done by considering a batch reactor in each cell of the simulation domain containing user-defined reactive processes of interest.…”