precipitation around grains in porous medium

Hi,

I am trying to build a model where the idea is that after a chemical reaction CaCl2 + Na2CO3 => CaCO3 (s) + 2 NaCl. CaCO3 precipitate and is immobile.

I am using the Reaction Engineering (re), with a generate space-dependent Model 2D Species Transport in Porous Media (chpm) and Darcy Law (dl).

Due that CaCO3 precipitated the porosity decrease of the porous medium. I want to solve it with a moving mesh (ale). I have made the velocity of the moving mesh dependent of the concentration CaCO3 and coupled the moving mesh change to the porosity in the Darcy Law. It is interacting, but not fully as I want.

I attached a picture where a segment of the porous medium, the holes represent the grains that need to grow.

My questions is:
Is it possible and how to do it, to control the moving mesh so that it only "grow" when the concentration of CaCO3 is a particular value at the grain. And that it wont shrink after the concentration decrease.

Is this a good method or do I need to put in PDE's?
I hope somebody can help me.

Thank you for your time!

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Barend