Amount of water in solution 1-cells

[Olasz Tamas]

Hi,

when using TRANSPORT you specify the amount of water in both SOLUTION 0 and SOLUTION 1-CELLS. The amount of water in SOLUTION 0 is the water flushing through the column, and it is the amount that is transported in each timestep in one cell. This is also what counts when the amount of solid phases are calculated to mol/L of contacting water, if I understand it correctly. Is this an analouge to the water filled porosity in the cells?

But what about the amount of water specified in SOLUTION 1-CELLS? What does that define, the initial amount of water in the cells which contains the initial ions? And if for example the amount of water in SOLUTION 1-CELLS is 0.5, and in SOLUTION 0 it is 0.7, then 0.7 kg water flows through the cells, which only contain 0.5 kg water? So that would be an analouge to the water filling in the air filled porosity? And does that influence any molalities/solid amounts?

[dlparkhurst]

Normally, the volume of SOLUTION 0-cells should be the same. There may be cases where this is not true, perhaps if you are using MIXes to do transport, but usually, the volumes should be the same.

If SOLUTION 0 were 0.7 L and 1-cells 0.5, then after each shift, one more cell would have a solution volume of 0.7 (with 0.5 in the rest) until "cells" shifts, in which case all cells would have 0.7 L of solution.

Often, ~1 L is used for the SOLUTIONs, and then the reactants for cells need to be defined as the number of moles reacting in L of water. If you prefer, you can use a fraction of a liter for the solutions (corresponding to porosity) and think of the cells as 1 L of porous media. Of course, the moles of reactants would need to be scaled accordingly.

[Olasz Tamas]

Thank you, that makes it clear.