Recompiling EOS1 for using LUBAND

Tony,

You would have to increase MNEL or MNCON or MNEQ dramatically until NRWORK = 1000+(MNEL+2*MNCON)*MNEQ*MNEQ+38*MNEL*MNEQ exceeds the number indicated in the error message you find in output file  (most likely exceeding the 2GB limit on a PC).

In short, I doubt switching to LUBAND is the solution, because:

(1) You may not be able to compile the code due to memory limitation

(2) Even if you can compile, it will likely run extremely slowly

(3) It is likely not to resolve the underlying issue (i.e., convergence problems)

Point (3) is the crucial one. Playing around with the solvers hardly ever helps. Here is what I would do:

(1) Find the reason for the convergence failure (I've described this diagnostic process in various  Forum posts)

(2) Try Karsten's "0=0" tip, i.e., initialize the system with a small amount of traced water and/or inject traced water along with fresh water.

(3) Check all properties of the fracture and matrix continua, specifically when they have huge contrasts. Properly adjust relative permeabilites and/or capillary pressures (depending on the result of Step (1).

(4) Set MOP(21)=2; try Z4 and O4 (don't get your hopes up playing with the solver options!)

Hope this helps.

Stefan

Follow up question: I am trying to model a problem with elements of 62,000 and connections of about 200,000. I increased MNEL to 70,000 and MNCON to 210,000. After compiling with these changes in T2 and running the new executable, I get the following error:

"THE NUMBER OF NEEDED DIAGONALS IS3721 WHILE THE AVAILABLE NUMBER IS  298. THE PARAMETER NRWORK MUST BE INCREASED TO AT LEAST  230,702,000"

However, if I just only increase the MNEL to 70,000 without increasing MNCON, then it does not show any error. But it does not give me any output either and reaches to the end of simulation. Do I need to increase (like you said) one of MNEL or MNCON or MNEQ or all of them?

Thanks,

Mamun

Mamun,

I do not recommend to run a 62,000-element (probably a 124,000- or 186,000-equation) model using a direct solver such a LUBAND. Did you try one of the iterative solvers now that you know how to "correctly" calculate 0=0?

Stefan

Thanks, Stefan for your reply. The link '0=0' does not seem to work. Could you please give me the correct link?

Mamum,

I'm confused - I thought you figured it all out about "0=0". Anyway, here is the link (you find it under "Help Articles", "Tips & Tricks" on this very Forum; let me know if it does not work for you):

http://esd1.lbl.gov/files/research/projects/tough/support/00.pdf

Stefan

Thanks, Tony - I'm easily confused...

Tony,

Thanks for the clarification. I am just using a single phase, single component problem with large a number of elements. But for some reason, I was having trouble in the MESH generation process after modification in T2. Anyway, I have figured it out. It was an elementary question for TOUGH community.

Thanks Stefan for your response.

Regards,

Mamun