outlet conditions used as inlet boundary conditions

[Eppner]

Hello,
I am trying to simulate dissolution and precipitation of CaCO3 in a column filled with sand. I impose an inflow at the top of the column and an outflow at the bottom. It's a closed loop and the water at the bottom is reused at the top of the column. How can I take concentration profil at outlet and use it for inlet boundary condition?

Thank you for your help.

[dlparkhurst]

I think you will have to run one transport step at a time.
The simplest way is to TRANSPORT one shift, COPY the last cell solution to solution 0, then run another TRANSPORT step. Note in succeeding TRANSPORT definitions, you only need to define the properties that change from the previous definition.

TRANSPORT
-shift 1
...
END
COPY n 0
END
TRANSPORT
-shift 1
END

You would have to repeat the sequence for each shift. Alternatively, you can use a scripting language and IPhreeqc to repeat this sequence under scripting control.

[dlparkhurst]

On second thought, you may be able to do it more simply with MIX.