OGS-Phreeqc reaction not occurring in the entire domain

[sumanab24]

Hi,

I am facing a problem. Can anyone please help me out with this ?

It is a simple groundwater flow and mass transport problem with OGS-PhreeqC. (it is a 0.5m 1D domain)

The two attached input files are same except : 

1) in initial condition file no boundary condition has been set for the reactants, only initial concentrations of 20 mol/kg has been provided for the reactants at point0. Here in the output file (pds_domain_line.tec) I can see that the entire domain is filled with the reactants and the product (calcite) after a certain time.

2) in the boundary condition file, I have set the initial concentration as 20 mol/kg and the boundary concentration as 5 mol/kg at point0. But in the output file (pds_domain_line.tec), I see that though the entire domain is filled with reactants, the reaction is taking place only in the first 10 cm (even if I increase the time and concentration, there is no effect). I want the reaction to take place in the entire domain.

Could you please help me to find out where I am wrong? (sorry for my bad concept in modeling) 

Thank you so much for your time and help.

Sincerely,

Sumana Bhattacharya

[Christof Beyer]

Dear Sumana,
please check the phinp.out file, which shows detailed phreeqc output for
the reactions at each grid node:


...

Beginning of initial solution calculations.
-------------------------------------------

Initial solution 7.

WARNING: Maximum iterations exceeded, 100

WARNING: Maximum iterations exceeded, 100

WARNING: The program has failed to converge to a numerical solution.

The following equations were not satisfied:
ERROR: C(4) has not converged. Total: 4.967901e+00
Calculated: 2.137134e+00 Residual: 2.830767e+00

ERROR: Ca has not converged. Total: 4.967901e+00
Calculated: 2.418773e+00 Residual: 2.549128e+00

ERROR: H(1) Charge balance has not converged. Residual:
-5.639697e-01

ERROR: A(H2O) Activity of water has not converged.
Residual: 1.605228e+01

-----------------------------Solution
composition------------------------------

Elements Molality Moles

C(4) 2.137e+00 2.137e+00
Ca 2.419e+00 2.419e+00

----------------------------Description of
solution----------------------------

pH = 12.032 Charge balance
pe = 11.370

...


ERROR: Model failed to converge for initial solution 7.

Stopping.


Phreeqc quits at the 7th grid node, so there probably is something
fatally wrong in your model setup.

Best regards, Christof

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--
_______________________________________
Dr. Christof Beyer
Institute of Geosciences
Geohydromodelling
Christian-Albrechts-University Kiel
Ludewig-Meyn-Str. 10
24118 Kiel
Germany

phone: +49(0)431-8803172
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_______________________________________