Lian Wang Posted September 23, 2023 Share Posted September 23, 2023 to the technical support team of GWB, your user's manual claims that it is possible to calculate sorption with constant capacitance model and constant potential model as special cases of DDL model on oxides. I tried with the input 'surface.rea' provided by the code and set the surface capacitance to 2 F/m2, see attached input. The run went ok and I got the result (also attached). It is however surprising that the ratio of the surface charge density and the surface potential, i.e., the defined capacitance is neither the value of 2 F/m2 and nor a constant value - as it should be for a constant capacitance model. E.g., the initial system has a surface charge = 5.23 uC/cm2 and the potential 53.4 mV so the ratio is 0.98 F/m2, not 2 F/m2. Did I miss something here? or I understood the definition of CCM wrongly? I am using the latest version GWB 17.0.1. The database is the 'thermo.tdat' and the surface data 'FeOH.sdat as provided. Thx in advance for any tips, CCM Surface.rea CCM Q React_output.txt Quote Link to comment Share on other sites More sharing options...
Jia Wang Posted September 26, 2023 Share Posted September 26, 2023 Hello, Thank you for attaching the relevant files. This might be a bug in the software relating to capacitance settings. We are looking into this more closely now. I apologize for any inconvenience. Best regards, Jia Wang Aqueous Solutions LLC Quote Link to comment Share on other sites More sharing options...
Lian Wang Posted September 26, 2023 Author Share Posted September 26, 2023 Hi Jia, Thanks for your response. Although no solution yet I appreciate your timely reaction so I don't spend time on my part searching for reasons. One thing you can try, if it is a useful suggestion, is to run it with one of the older versions (maybe version 10). I think I did run CCM with an older version and it was fine but I am not sure. Constant capacitance model and constant potential model features existed from very beginning of the GWB. By the way, the constant potential feature seems working fine in the current version. regard, Lian Wang Quote Link to comment Share on other sites More sharing options...
Jia Wang Posted October 2, 2023 Share Posted October 2, 2023 Hello Lian, Thank you for bringing this issue to our attention. We have made a fix to the issue with regards to constant capacitance in model runs. To get you and other affected users up and running now, we have created a release candidate installer. To download, use the link below. GWB17.0.2rc2_setup.exe The fix will be included in the next maintenance release. Please let us know if you run into any other issues with the release candidate. Best regards, Jia Quote Link to comment Share on other sites More sharing options...
Lian Wang Posted October 8, 2023 Author Share Posted October 8, 2023 Hi Jia, thank you for the fix. I run some test inputs and it seems working as expected. I have however another question/suggestion/discussion related to the use of CCM in particular and the use of 'react' in general. The system I am modelling can be in general described as a system containing mineral surfaces with a constant capacitance. With your fix now I am able to run it with a given capacitance value. However, the system capacitance is a function of solution ionic strength, I, so I need to give the C value calculated by hand for the given ionic strength. A better way, and a more general way, is to be able to let the code calculate the capacitance as a function of ionic strength automatically so the model can be run for varying ionic strength but not only for one ionic strength per input. I hope I explained myself clearly. In other words, is there a way to input capacitance as a function of I, but not as a fixed numerical value as it is now. In general, this is like what the 'field variable' is allowed in Xt codes there one may define a field variable which changes in the course of the run. To my understanding there is no such field variables can be used in 'react' now. Is there a way around to allow a field variable in 'react' code? Once again thx a lot for the fix, it helped a lot. best regards, Lian Quote Link to comment Share on other sites More sharing options...
Jia Wang Posted October 10, 2023 Share Posted October 10, 2023 Hello Lian, Thank you for your suggestions but we currently do not have plans for this adding this feature. I will make sure to pass your suggestions onto relevant hands. Best regards, Jia Quote Link to comment Share on other sites More sharing options...
Jia Wang Posted October 17, 2023 Share Posted October 17, 2023 Hello Lian, The issue with setting constant capacitance in model runs is now corrected in the maintenance release 17.0.2. If automatic update is enabled, you should be prompted to update in the next few days when you open the GWB dashboard. You can also manually update by going to check for updates under the "Help" menu of any app or on the Support pane of the GWB dashboard. Best regards, Jia Quote Link to comment Share on other sites More sharing options...
Lian Wang Posted November 6, 2023 Author Share Posted November 6, 2023 Hi Jia, thanks a lot for informing me. Will install it when available. best, Lian Quote Link to comment Share on other sites More sharing options...
Jia Wang Posted November 6, 2023 Share Posted November 6, 2023 Hello Lian, I hope you enjoy using the software. Best regards, Jia Quote Link to comment Share on other sites More sharing options...
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