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Re: non-convergence


The radium01.txt runs (converge in that sense), just
give gabage results. I did remove the knobs data

--- David L Parkhurst <dlpark@xxxxxxxx> wrote:
> > I have run into a couple of non-convergence with
> phreeqc lately. I have attached 3 input files. The
> file radium01.txt attempts to simulate solid
> solution
> formation (Ra,Ba)SO4 in a reactive transport regime.
> I
> have tested the same solid solution model without
> transport, and it ran fine. When there is transport,
> it  does not converge, and also, it simply gives
> equal
> mole fraction of the two end-members. Additionally,
> I
> suspect that the equilibrium sulfate and barium
> concentrations are shifted a little, that is, the
> product or IAP is right but the relative activities
> of
> sulfate and barium are shifted.
> If you remove the KNOBS data block, the file runs.
> If there is still a
> problem with the mole fractions, let me know.
> > The file kinetics qrtz2.txt attempts to simulate
> reactive transport when quartz kinetics is involved.
> It does not converge. The kinetics01alb.txt for
> albite
> dissolution converged. So does a similar file for
> K-feldspar. However, when I have both albite and
> k-feldspar kinetics, it did not converge.
> I'm not sure what you are trying to do here. With
> the number of minerals in
> EQUILIBRIUM_PHASES, the activity of H4SiO4 is
> probably nearly invariant. I
> ran a little test adding a millimole of  SiO2 and
> the solution composition
> barely changed. Adding kinetics of quartz to this
> system may not make much
> sense. I'm not sure if albite/k-spar is related or a
> different problem.
> > Separately, I am going to attend GSA in Denver. If
> you
> are still interested in conducting a short course
> next
> year, I can come in early or stay late for
> discussions.  I have taught a geochemical modeling
> course for a semester and you probably have some
> teaching materials too. I don't think it will take
> that much time to prepare the short-course.
> I think I really do not want to teach a short course
> at GSA. There are too
> many other things I'd rather do and time is always
> at a premium.
> David
> David Parkhurst (dlpark@xxxxxxxx)
> U.S. Geological Survey
> Box 25046, MS 413
> Denver Federal Center
> Denver, CO 80225
> Project web page:
> https://wwwbrr.cr.usgs.gov/projects/GWC_coupled

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