Crystal dissolution and precipitation in porous ...

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XVI International Conference on Computational Methods in Water Resources (CMWR-XVI) Ingeniørhuset

Crystal dissolution and precipitation in porous media flow: variable geometry
Paper
Author:Tycho Van Noorden <t.l.v.noorden@tue.nl> (Eindhoven University of Technology)
Sorin Pop <ipop@win.tue.nl> (Eindhoven University of Technology)
Hans Van Duijn <c.j.v.duijn@tue.nl> (Eindhoven University of Technology)
Presenter:Tycho Van Noorden <t.l.v.noorden@tue.nl> (Eindhoven University of Technology)
Date: 2006-06-18     Track: Special Sessions     Session: Multi-Disciplinary Approaches To Reactive Transport Simulation In Aquifer Systems
DOI:10.4122/1.1000000469
DOI:10.4122/1.1000000470

In this work we propose a pore scale model for crystal dissolution and precipitation in a porous medium. Our investigations are a first step towards an upscaled model for crystal formation in reactive porous media flows and are motivated by the work of P. Knabner et al. (Adv. Water Res. 1995) and C.J. van Duijn et al. (J. reine angew. Math. 2004). We consider a porous medium that is fully saturated by a fluid in which cations (e.g. sodium ions) and anions (e.g. chlorine ions) are dissolved. In a precipitation reaction, n cations and m anions can precipitate in the form of one particle of crystalline solid (e.g. sodium chloride) attached to the surface of the grains (the porous matrix). The reverse reaction of dissolution is also possible. As a result of the precipitation and dissolution of crystals the geometry of the flow domain may change. The model we propose consists of a system of coupled partial differential equations on a variable domain. The changes in the flow domain, which occur due to the dissolution and precipitation of crystals are modeled by a Stefan-like boundary condition. This describes the movement of the interface between the fluid and the crystal layer. For simple geometries we show that solutions exist and we study their qualitative behavior using both analytic and numerical techniques.