How to improve the stability of the numerical results without changing the grid discretization ?
Dears,
I have the following simulation case for CO2 injection in stratified aquifer using 2D grid model. I have slight fluctuations in the pressure results. I have tried to improve the numerical settings to decrease the instability while keeping the grid discretization unchanged, however I still have the instability in the results. I would like to know if these results can be improved (decrease the instability) while keeping the grid discretization unchanged?
Thanks in advance
4 replies
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I can think of one easy thing for you to try: increase rock compressibility COM (second line in ROCKS entry for each material). Your current value of 3.71E-10 is pretty small. Try increasing by a factor of 10 and see if that helps.
Your radial grid spacing changes rather abruptly (DR goes from 0.18 to 1.8, 1.8 to 9, 10 to 100). I have had trouble in the past with CO2 injection when the grid spacing changes by more than a factor of 2. If you are willing to make a new grid, I recommend using the LOGAR feature of MESHMAKER to get a gradually increasing radial grid spacing.
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I agree with Christine Doughty that you need more gradual spacing, but perhaps it’s worth a shot to limit the size of your time stepping purposefully. In addition to changing the tolerance in PARAM 3, you could use the DLT feature in param to set them manually. Ultimately, though, I think it’d be more effective (and probably easier) to use LOGAR in Meshmaker, like Chris suggests.