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Posts posted by Karen
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Nevermind. I sorted this question out.
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Brian,
I have a questions about an older model/script in x1t that used to run fine on my previous version (version 9) but now seems to get hung up by not converging on the element I chose for charge balance on my new version 11. I know that a general approach for non-conversion is to increase the number of iterations or decrease the tolerance. I am attaching a screenshot. I guess, I am not sure what the best way to fix this general issue in GWB. Suggestions?
Karen Johannesson
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Thanks again Brian!
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Hi Brian,
Great! I will pop by the GWB booth and say hi.
Quick question, does the BASIC language that GWB employs for such custom rate laws use log for log base 10? When I used to use BASIC decades ago, LOG was for the natural log. I have rate law expression that is given as:
log Rate = 0.03*pH2 - 0.073*pH - 10 that I need to "code" for one of the minerals in my hypothetical basalt. Based on what you wrote above, I will need to convert "log R = ..." to "R = ..." using activity("H+") for the pH terms. In my olden days of BASIC programming to code for log base 10, I would have to use "2.303*LOG(argument).
Karen
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Thanks Brian,
This is very, very helpful!
Are you planning to attend GSA in Baltimore in a few weeks? If so, hope to see you there.
Best wishes,
Karen
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Thanks Brian! This helps a lot.
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Brian,
I am interested in writing some custom rate laws into a script for dissolution of some minerals. I have an idea as to how to do this but I think I am possibly missing something critical. Below is a rate law for anorthite dissolution that is one of the simpler expressions I am interested in incorporating into a React model. It has the form:
Rate = k+[((aH+3n/aAl3+n)Keq)/(1+Keq(aH+3n/aAl3+n))]
where n = 1/3, Keq is a known constant, and k+ is the forward rate constant. "a" represents activities and the parameters with n in them are exponents on the various hydrogen ion and aluminum ion activities. I have attached a file with a better representation of the expression. Also, I have not included the surface area of the (1-Q/K) terms because those are obvious to me as to their implementation. Any suggestions you have would be greatly appreciated.
Best wishes,
Karen J.
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Hi Brian,
Thanks for your reply. I followed your advice and it worked. So, in case anyone else reads this, the modified scatter data for the case of Mg++ that works is:
# Act2 scatter data for activity diagram"SiO2(aq)" "Mg++" "H+"--------------------------------4.5052 -1.9982 -8.03 blue blot-3.4015 -2.638 -6.9 green triangle-3.3841 -2.5328 -7.15 red blot-3.3813 -2.74 -7.55 red triangle-3.4283 -2.6321 -6.76 red square-3.3579 -2.8465 -7.7 green squareBest wishes,Karen -
I am wondering why I can plot scatter data onto an activity diagram (ac2 plot) of log [K+]/[H+] vs. log [siO2(aq)], where [ ] indicates activity, but when I try to plot a similar diagram for log [Ca++]/[H+]^2 vs. log [siO2(aq)], I get the following error
"scat: Can't plot scatter data; doesn't contain: log ratio Ca++/H+^2".
The scatter data "scripts" that I have been using are the follows:
# Act2 scatter data for activity diagram"SiO2(aq)" "K+/H+"----------------------4.5052 5.8563 blue blot-3.4015 4.0147 green triangle-3.3841 4.3142 red blot-3.3813 4.6157 red triangle-3.4283 4.0639 red square-3.3579 4.5173 green squareand:# Act2 scatter data for activity diagram"SiO2(aq)" "Ca++/(H+)^2"--------------------------------4.5052 12.924 blue blot-3.4015 10.2125 green triangle-3.3841 10.6879 red blot-3.3813 11.3482 red triangle-3.4283 9.8096 red square-3.3579 11.6956 green squareAgain, the one for potassium works fine, but the one for calcium is right out.
Thanks,
Karen
Dual Porosity
in The Geochemist's Workbench
Posted
I am wondering if there are any people on this forum who are more of a "hydrogeologist" than a geochemist who could recommend appropriate parameters for the dual porosity "module" of GWB for a unconsolidated sand aquifer that has an average porosity of 25%.