iamseanty

Hi Brian, The built-in rate law doesn't work for our case, because the dissolution rates of the carbonates in our system are dependent on three promoting species with three sets of parameters (pre-exp, Ea and power)... we have to use script (or something similar, like equation or script file) to account for these effects. At 25C, the script works because the carbonates are not fully consumed in the system, and the model finished without any problem. When T was increased to 80C or 100C, sulfides and carbonates react a lot faster, causing carbonates running very low after several days and model crashed soon due to convergence issue during the simulation. The testing x2t input file just provided an example for this. We have to simulate higher temperature for this project, so your help to solve this problem is greatly appreciated. Thanks and regards Yuan

Hi Brian, if you have time, could you please have a look? The functionality of custom-built kinetics are critical to our project.. and we would like to resolve this problem with your help. Thanks and regards Yuan

Hi Brian, Thanks for your email. Yes, we used thermo.com.V8.R6+.tdat. We modified test2.x2t input file following your suggestions. And this time the model ends up with convergence issue at 0.095%, this is where dolomite is mostly consumed (~1.67e-62). So this is like a puzzle again why test1 can run without any convergence problem and test2 can't? I attached the modified test2.x2t for your consideration. Test1.x2t is unchanged. Could you please have a check? Thanks Yuan test_2_mod.x2t

Hi Brian, Thanks for your reply. I checked the details as you suggested and I found that this is all because of the carbonates are consumed (very close to zero) at 80C at ~18% of the simulation, which forces the model to constrain time step in response of the change of mass of dolomite. Here I attach two simplified X2t input files for comparison. They are mostly the same except for the way of expression of dolomite dissolution kinetics: test1.x2t uses the default built-in rate law and test2.x2t uses a script, of which the rate formula looks the same as test1 input file. The difference is that: test1 can run till the end of simulation without any issue; however, test2 runs to ~0.09% of the simulation and gets stuck then. That is when dolomite in node1 is close to zero... Do you have any idea of the cause of such discrepancy from the two input files? Thanks Yuan test_1.x2t test_2.x2t

Hi there, I am using X2t to do reactive transport modelling. My model runs successfully at 25C, 100% finished. But after I increase temperature to 80C, the model progress stays at 18.32% and won't proceed anymore... It's strange that the model doesn't crash and looks still busy running... Do you have any idea about this issue? Thanks and regards Yuan