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transport - mixture 1
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Topic: transport - mixture 1 (Read 85 times)
zsszabo86
Frequent Contributor
Posts: 13
transport - mixture 1
«
on:
May 14, 2019, 03:09:34 PM »
Hello
I have run into two problem which I did not see before. I run reactive transport simulations and want to model a scenario when CO2 containing water flows into a geological formation. I have problems with both ways I figured out:
1. I start the code like this:
SOLUTION 0
temperature 135
pressure 272.8
units mol/kgw
pH 5.029
pe 5.059
Al 1.92E-06
C(4) 4.99E-01
Ca 2.03E-03
Cl 4.93E-01
Fe 4.26E-06
K 4.05E-02
Mg 2.16E-03
Na 4.63E-01
S 5.13E-02
Si 5.45E-03
GAS_PHASE 1
-fixed_pressure
-pressure 272.8
-volume 5000
-temperature 135
CO2(g) 272.8
SAVE solution 0
END
USE solution 0
etc.
then it seems that the gas phase can be completely used up and then there is no more CO2 coming into my cells with solution 0 (even though I believed that the saved solution 0 is CO2-saturated). other words: it seems that not the new saved solution 0 is used and it also seems that the gas phase is used not only for calculating the solution 0 composition but it is in all cells
it would be great to get some explanation of what is happening
2. The other way was to simulate the CO2-containing solution in a different model then to copy paste the result as the solution 0. it seems ok to do that but then no reaction happens. and looking at the output I see that the solution 0 is not flowing into cell1. see below 0.000e+00 Solution 0 and also see in attachment.
Mixture 1.
0.000e+00 Solution 0 Solution after simulation 2.
6.677e-01 Solution 1 Solution after simulation 2.
3.323e-01 Solution 2 Solution after simulation 2.
Again, I cannot figure out why the solution 0 is not flowing in and advice would be helpful.
Thank you in advance!
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dlparkhurst
Top Contributor
Posts: 1411
Re: transport - mixture 1
«
Reply #1 on:
May 14, 2019, 09:50:58 PM »
Assuming you are using TRANSPORT, solution 0 has the additional CO2 needed to produce a partial pressure of 272.8, and it will be advected into the column with each shift, provided you have specified a flux boundary condition at cell 1.
If you specify diffusion only, solution 0 will not be advected into the column.
Not sure about a constant boundary condition, but I think cell 1 would be maintained at the solution 1 composition, and solution 0 would not affect the calculation.
Alternatively, you can specify GAS_PHASE 1, which would continue to react with cell 1 throughout the calculation, although the CO2(g) pressure will continuously decrease. You may want to specify CO2(g) in EQUILIBRIUM_PHASES 1, which would maintain the CO2(g) partial pressure throughout the simulation (provided you give a large amount of moles in the definition).
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zsszabo86
Frequent Contributor
Posts: 13
Re: transport - mixture 1
«
Reply #2 on:
May 15, 2019, 09:34:44 PM »
Many thanks for the useful reply! It finally opened my eye, what the problem is (it is diffusion only!!!) and how to solve it.
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transport - mixture 1