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Hi all,

I am running a reactive transport model where I apply  a vertical and horizontal fluid to a reactive transport model that contains a variable abundance of hydroxyapatite. However, when the fluid it applied, the whole domain (approx. 800 x 20 m) becomes undersaturated w.r.t. hydroxyapatite almost immediately. When applying a fluid that is undersaturated I would expect this to happen, but over a much slower timescale.

Attached is the X2t file. Any advice would be appreciated.



Sam Bingham


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Hi Sam,

The inlet fluids don’t infiltrate very far into your domain over the timescale of your simulation, let alone by the first step in the plot file. You can plot “pore volumes displaced” or add a conservative tracer to verify this. And looking at the Q/K for Hydroxyapatite, I don’t think it ever gets undersaturated in most of the domain, it just approaches equilibrium – a log Q/K of ~0. The Hydroxyapatite is supersaturated in the initial porewater, and I think it’s just precipitating really quickly, and thus approaching equilibrium very quickly. The undersaturated inlet fluid doesn’t really come into play here.

I think it would be a lot easier to troubleshoot a scenario like this with a 1D model in X1t, or even a flush model in React.

Hope this helps,

Brian Farrell
Aqueous Solutions   

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