kateduke

Hi Brian, That would be great. No worries about response time--I appreciate you being willing to try to find a solution. Thanks, Kate

Hi Brian, What I'm trying to do is represent a "shrinking core" kinetic model. I have a rate law from experimental data that describes the initial rate of a leaching reaction that I put in the "rate law" line. And then I have another relationship (developed from multiple dissolution experiments) that describes the decrease in the leaching rate over time as a function of the progress of the leaching reaction (the overall reaction rate is decreasing due to the rate at which the reactants and products diffuse through the increasingly deep leached layer on the surface of the mineral and due to the decreasing concentration of the reactants (in this case H+) with time). This relationship I am putting in the "rate constant" line. So I'm basically using a time-variant rate constant that is based on the reaction progress to represent the shrinking core kinetics. This works well in React where I can specify the initial mass of the mineral and then hard-code that value into the rate constant equation. However, the next step is to bring this kinetic phase into X2t where the initial mass of the mineral will be heterogeneously distributed so I'll no longer be able to hard code that initial mineral mass into the rate constant equation. What I would like to be able to do is to write the rate constant equation in terms of the initial mineral mass for any given nodal block--e.g. rate constant is a function of the concentration in the fluid at each time step (e.g.[Ca]) divided by the initial mass of the mineral from which the Ca is being leached (e.g. a Ca-silicate). I tried doing this using Xi but Xi goes to one (1) at the end of the time period (which drives the rate to zero) whereas, depending on the fluid composition, there may still be Ca left in the mineral phase at the end of the model time period. So I'm wondering if there is a variable name that I can use to call that initial mineral mass as part of the rate constant equation--e.g. [Ca++ in solution]/(Initial Mass Ca-silicate). I hope this clarifies my question. If not, I can send you the input file via email. Thanks, Kate

Hi All, What is the name of the variable that represents the initial mass of a reactant? That is, if I start with 0.5 grams of calcite, and I want to calculate the reaction progress as a function of the Ca in solution divided by the original Ca mass (in the calcite) how do I represent the initial Ca or calcite mass in an equation or script? Thanks, Kate

Hi Brian, I reset the configuration in Xtplot but it still can't open the plot file. I reran the simulation with simpler chemistry and everything works fine--both the model and the plot. The plot file that I can't open is huge--even zipped it's over 100 MB. Maybe I'll leave it for now--if I run into the same problem down the road as the model gets more complex I'll send it to you via Dropbox (or whatever your file management preference is). Thanks for your response, Kate

Hi All, I am working on a reactive transport simulation which seems to be running just fine--the simulation ends and tells me that it was successful. But Xtplot gives me an error message that says that the "input file is not in correct format". I can see the X2t_plot file in the directory and it looks like it was updated (it is about 450 MB). Any suggestions as to what might be happening? Is the X2t_plot file too big? I don't understand why the simulation appears successful but the plot file is not correct. Any help would be greatly appreciated. Thanks, Kate