RTSOL keyword. Problem 4 (*rtp7*) - CO2 Injection using ECO2N for TOUGH2-MP
Hi! I am using TOUGH2-MP with the ECO2N module.
In the install directory "eco2n/rtp7", I find the INFILE for the test case " Problem 4 (*rtp7*) - CO2 Injection into a 2-D Layered Brine Formation".
However, this INFILE is slightly different from that given in the ECO2N user manual. I suspect the difference is due to that I use TOUGH2-MP, whereas the INFILE given on page 58 in the manual is for TOUGH2?
Anyway, I have a question regarding the RTSOL keyword in this INFILE.
RTSOL prec rtol info iplvl nitmx nort kacc iredb 1.0e-6 0.1 0 1 250 15 2 0 1.e-5 1.e15 100.0 100. 2.00 0.20 0.2 0
In Record RTSOL.2, we find the two fields DSTNOM and DXTMAX, however only DSTNOM seems to be documented in the TOUGH2-MP user's guide on page 50. It says:
maximum allowable saturation change per time step (default=0.2).
As can be seen, this value was initially set to 100.0.
I wonder, why was this set so high? I thought saturation would stay between 0 and 1.
Last question: What is the purpose of DXTMAX, and why is it also set to 100.0 ?
( I suspect, my confusion is related to mistake in the ordering of the fields on page 50 in the TOUGH2-MP user's guide. Here it gives the following ordering for RTSOL.2:
DTMIN, DTMAX, DSTNOM, DXTMAX,TMULFC, RELXSN,
So DXTMAX should be field number 4, from the INFILE it seems that the correct position should be field number 6 or 7 (since these have a 0.2 value))
Only the first and the third are actually used. The rest are for a solver that is not bundled with TOUGH2-MP since it is proprietary. In addition, setting DSTNOM to 100 inactivates the criterion where a solution step is restricted by the maximum change in saturation. You can use any arbitrarily large value for this purpose of course.