Dual Domain Transport of U and Cl

[davidblevy]

I am trying to evaluate the effects of dual domain porosity (stagnant cells) in a 1D reactive transport model on the predicted transport of U and Cl. However, I am not seeing any differences in the timing or concentrations of constituents between model runs with and without stagnant cells. I have adjusted various parameters (cell size, porosities, dispersivity, etc.) and still see no differences. I was able to see the differences when running one of the example files, with and without stagnant cells. Any feedback as to why this model is insensitive to including the stagnant cells would be appreciated, thank you. David.

[dlparkhurst]

You will need to define SOLUTIONs (and reactants) for the stagnant cells 26-49, and you will need to define a time step.

Debugging suggestion:

Do not turn off printing (no -reset false). Start with a single conservative constituent, simple solutions, and no reactions.

[davidblevy]

It looks like things are working and I have a better understanding of how the stagnant cells are defined, thank you! David

[davidblevy]

Things get a little trickier when expanding this type of model to contain four zones with different aqueous chemistry, in the attached file we have: Cells 1-3 (Zone 1), Cells 4-30 (Zone 2), Cells 31-56 (Zone 3), and Cells 57-73 (Zone 4). When a single immobile cell is added to each mobile cell, I believe the solutions which need to be defined now become 1-7, 8-62, 63-115, and 116 -150. Can you please verify if this is correct, and that using the first of each mobile cell solution (Solutions 1, 4, 31, and 57) for equilibration with the surfaces is correct?

Also under TRANSPORT, I am specifiying 73 cells (which is the number of mobile cells), but using PUNCH_CELLS 132 to output the concentrations at the end of the column, which I believe is the last mobile cell. Although the output chloride does not match the concentration in the last group of cells (Zone 4), looking at the output (I did a single PV run with PRINT turned on), I see there is mixing with upgradient cells (which I have not fully understood yet), so maybe use of cell 132 as the last mobile cell is correct? Any input would be appreciated, thank you!  David

[dlparkhurst]

When you define TRANSPORT with -cells 73, the mobile cells are numbered 1-73. Immobile cells are numbered 75-147. Connections are between cell n and cell n+74. Cell numbers 0 and 74 are used for boundary conditions.

[davidblevy]

Thank you for the rapid response, I will give this a try! David

[davidblevy]

I re-adjusted the cell numbers and associated solutions/phases and the results seem much more resonable now, thank you again. David