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Chemplugin: resize system and fluid


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I am using Chemplugin 14.

In my model I have 4 nodes and want to keep the solution volume constant.

I have a list that I want to reset the fluid volume to:

               list_SolVol = [0.6, 1.7, 0.5, 1.4, 1]

like this:

               for i in range(nx):
                           cp[i].Config("resize fluid " + str(list_SolVol[i]) + " m3")


However, chemplugin seems to change the bulk volume and not the solution volume. I check it through:

for i in range(nx):
            print("solvol: ", cp[i].Report1("soln_volume","m3"),"volume node: ",cp[i].Report1("bulk_volume","m3")," PV : ",cp[i].Report1("PV"))

Here is some print output at some timestep:

solvol:  0.026172303693188213 volume node:  0.5999999999999999  PV :  6.0001677297425
solvol:  0.08568825050586173 volume node:  1.6999999999999993  PV :  2.1177062575561734
solvol:  0.0585576969381515 volume node:  0.49999999999999983  PV :  7.200201275691004
solvol:  0.020309748395506474 volume node:  1.3999999999999997  PV :  2.571500455603926
solvol:  0.02229226342265376 volume node:  1.0  PV :  54.00150956768248


Could you maybe check if this is correct.....




Not directly related to the above; if I want to introduce evaporation to a node through

    react -400 kg/year H2O

it seems that this does not influence the solution volume (it will just concentrate up the solution by the removal of a parameter H2O).

Is this correct? So if I want to change the solution volume through evaporation I will also have to use the resize function?

Is there another way to introduce evaporation?


In Chemplugin the bulk volume (for each node) changes as in React and does not stay fixed like in X1t and X2t?

So the bulk volume will also changes when the solution volume changes? It doesnt add inert volume? Basically, is there a difference how chemplugin and react handle changes to the bulk and solution volume (with or without evaporation). Sorry I havnt checked this in the model myself yet but maybe it is good to ask.




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Hello Johan,

I think ChemPlugin is resizing the fluid/node properly. I tried with a single node example and was able to resize the fluid correctly. I would suggest checking to see if resizing works on a single instance in your script first before applying it to all other nodes. 

With regards to question 2, removal of H2O will certainly decrease the solution volume and your system should become more concentrated. An example of this can be seen in evaporation.rea using React. The resizing feature in ChemPlugin will adjust the fluid volume to the desired quantity but preserves the concentration each species, so it is not really suitable for simulating evaporation. If you increase the inert volume, that wouldn’t affect the concentration of the species, it would just change the bulk volume of the instance. 

With regards to question 3, ChemPlugin doesn’t have any concept of geometry. The bulk volume of an instance is the sum of mineral, inert, fluid, and stagnant zone volumes.  As these quantity changes, the bulk volume will reflect these changes as well. The program won’t add inert volume due to the decrease of fluid volume to keep the bulk volume fixed. React and ChemPlugin are similar in that bulk volume can change as its constituent parts change, and that this is different from X1t and X2t, in which bulk volume is fixed.

Hope this helps,
Jia Wang

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