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Phreeqc crashes at higher volumes of water



Dear Dr Parkhurst:

In may 2001, we've had an e-mail discussion on transport.  I've been
away from the university, but now I'm back and I've solved the
problem.  I've developed a script which converts short input files
into long phreeqc input files which perform the transport calculations
I'm interested in.

There is a minor problem though.  Phreeqc runs tend to crash and I've
isolated the problem.  The following very short input file reproduces
the problems related to Phreeqc

SOLUTION 679
   -water 15.00 # 14.80 runs ok
   Ca 0.5 mol/kgw
   Cl 1.0 mol/kgw

END

I guess it is the combination of high water volume and relatively high
concentrations.  I've tested this code on versions 2.6, 2.7 and 2.8 of
Phreeqc, of which I've compiled the distributed source code at linux
SuSE 7.3 and 8.1 machines.  Lowering the volume of water to 14.80
makes Phreeqc processing the file smoothly.

Running Phreeqc on the code above produces the following output.

   chris@xxxxxx:~/modules/hit/calcs> phreeqc errorReproduction.phq
   Create a link databases.phq to phreeqc's database...
   Input file: errorReproduction.phq

   Output file: errorReproduction.phq.res

   Database file: /home/chris/wrk/docAndProgs/phreeqc/2.7/phreeqc2.7/database/phreeqc.phq


   Simulation 1.  Initial solution 679.
   WARNING: Maximum iterations exceeded, 100

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

   The following equations were not satisfied:
   ERROR:                   Ca has not converged. Total: 7.500000e+00      Calculated: 9.541005e-02        Residual: 7.404590e+00

   ERROR:                   Cl has not converged. Total: 1.500000e+01      Calculated: 9.030416e+00        Residual: 5.969584e+00

   ERROR:                   Mu Ionic strength has not converged.   Residual: 9.711428e+01

   ERROR:               A(H2O) Activity of water has not converged.        Residual: -2.273609e-01

   ERROR: Model failed to converge for initial solution.
   Stopping.

I hope you will be able to look into this problem.  I would like to
hear whether you see any solution for this problem.

Thanks in advance

Chris van Uffelen
Soil Quality
Wageninge


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