Dissolution and Precipitation in X2t and X1t

[elg0086]

Hi,

When a mineral precipitates in an X2t or X1t node, is it capable of redissolving if the system changes later in the simulation? Is there a way to remove precipitated minerals from the system? From what I understand porosity will reflect any changes in dissolution and precipitation.

Thanks,

-Erik

[Brian Farrell]

Hi Erik,

Yes, a precipitated mineral in X1t or X2t can later dissolve if the system changes and it becomes undersaturated. Regarding removing precipitated minerals, the flow-through configuration in React does this at each step of the calculation so that they don’t dissolve back into the fluid. The conceptual model is that you’re following the vantage point of a single packet of water flowing through an aquifer. It’s a “quasi” reactive transport approach. In X1t or X2t, though, you actually have a spatially discretized domain, so removing minerals isn’t necessary. A single packet of water won’t react with the minerals in an upstream node after it’s been transported away. You have a continuous addition of new packets of water, though, that should be able to react with the minerals they flow though. 

If you’d like, you can specify a custom rate law that would allow a kinetic mineral to precipitate according to one equation but dissolve according to another (perhaps set the rate to 0). That way the mineral doesn’t react, even though it’s still present.

Yes, porosity reflects any changes in mineral volume due to dissolution or precipitation.

Hope this helps,

Brian Farrell
Aqueous Solutions LLC
 

[elg0086]

Thank you!

 

-Erik