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# Can T2VOC simulate different grid increment ?

Can T2VOC simulate different grid increment ? For example, x= 0.1, 0.4, 0.5, y = 0.1, z=0.2, 0.3, 0.6. I found it does not run as usual.

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• Short answer: "yes, it can!". I cannot say more, as it is unclear what "does not run as usual" means. Make sure you design your irregular or unstructured grid appropriately.

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• Is my input below for mesh generation is correct?

For x = 0, 0.3, 0.5, 1.0, 1.5, 1.75, 1.9, 2.0, 2.25, 2.4, 2.5, 2.65, 2.75, 3.0, 3.15, 3.25, 3.5, 3.55, 4.0, 4.25, 4.45, 4.5, 5.0, 5.5, 6.0, 6.35

For y = 0, 0.14

For z = 0.5, 1.0, 1.5, 1.6, 1.65, 1.7, 1.8, 1.85,1.9, 2.0, 2.5, 3.0, 3.3, 3.35, 3.4, 3.45, 3.5, 3.55, 3.6,       3.8

*RAMSBURGMESH*...CREATE GEOMETRY USING MESH GENERATION AND PROCESSING
MESHMAKER1----*----2----*----3----*----4----*----5----*----6----*----7----*----8
XYZ
00.
NX                8           0.
0.3         0.5        1.0        1.5       1.75        1.9         2.0       2.25
NX                8           0.
2.4         2.5       2.65      2.75        3.0       3.15       3.25        3.5
NX                8           0.
3.55         4.0       4.25      4.45        4.5        5.0         5.5         6.0

NX                1       6.35
NY                1       0.14
NZ                8           0.
0.5         1.0        1.5        1.6       1.65        1.7         1.8       1.85

NZ                8           0.
1.9         2.0        2.5        3.0        3.3       3.35         3.4       3.45

NZ                8           0.
3.5       3.55        3.6        3.8

ENDFI--------1----*----2----*----3----*----4----*----5----*----6----*----7----*----8

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• Hi Nor,

Well, it's (almost) the correct format, but most likely not what you intended (I'm just guessing here). Please read the manual under MESHMAKER, and you will see that you have do specify grid SPACINGS, i.e., DX, DY, and DZ, not X, Y, and Z! Also, your last NZ block has only 4 instead of 8 entries. (By the way, you could combine all NX in one, i.e., "NX        25" followed by 25 DX values on 3 1/8 lines; same for NZ.)

Here comes my real advice: What you need to do is convince yourself that the resulting mesh is the one you really wanted. You do this by simply looking at the output and MESH files. You will immediately see that neither the element volumes, nor nodal distances, nor interface areas, nor X, Y, and Z coordinates are consistent with what you have in mind (again: I'm guessing). The same advice applies to any other input block.

Hope this helps.

Stefan

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• Thanks Stefan. Now I understand :)

By the way, one more question.

If I set TIMAX equal to 1.62e3 secs and run simulation. Then, from the output file shows data for the time other than TIMAX equal to 1.62e3, for example the time is 0.23e3 secs. What are the parameter influenced the time changed?

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• Nor,

Check variable MCYPR in PARAM.1 and block TIMES.

Stefan

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• Ok. thanks Stefan.

One more question. :)

If the mesh are as follows

A11 1                A11 2                A11 3                A11 4                 A11 5                A11 6                A11 7

A21 1                A21 2                A21 3                A21 4                A21 5                 A21 6                A21 7

A31 1                A31 2                A31 3                A31 4                A31 5                A31 6                A31 7

A41 1                A41 2                A41 3                A41 4                A41 5                A41 6                A41 7

A51 1                A51 2                A51 3                A51 4                A51 5                A51 6                A51 7

A61 1                A61 2                A61 3                A61 4                A61 5                A61 6                A61 7

A71 1                A71 2                A71 3                A71 4                A71 5                A71 6                A71 7

A81 1                A81 2                A81 3                A81 4                A81 5                A81 6                A81 7

A91 1                A91 2                A91 3                A91 4                A91 5                A91 6                A91 7

AA1 1                AA1 2               AA1 3                AA1 4                AA1 5                AA1 6          AA1 7

And I want to differentiate between these two layer in block ROCKS:

ROCKS----1----*----2----*----3----*----4----*----5----*----6----*----7----*----8
CSAND    1     2650.      0.40  8.0E-12 8.0E-12 8.0E-12         3.     1000.
0.      0.     2.85        0.0
IMPER    1     2650.       0.00  0.0E-11 0.0E-11 0.0E-11         3.     1000.
0.     0.      2.85       0.0

Layer 1 = CSAND without bold element

Layer 2 = IMPER with bold element

So, the solution is I just put 1 or 2 at block ELEME keyword MA2 right?

If I inject DNAPL at element A61 4, is there any possibility the DNAPL will spread between element A51 3 - A51 4 and between element A51 4 and A51 5?

Is there any parameter that I left?

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• Nor,

The answer is "yes" regarding assignment of rock types. You can answer your second question yourself: Just check whether you have a connection between the two elements in question, which would indicate that you can have direct flow between them (of course assuming a host of other conditions are fulfilled). If there is no direct connection, fluid may need to take a detour to arrive at the target element.

Stefan

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• Hi Stefan,

What does it mean by "failure on visco2"? How can I overcome this failure?

And if the simulation aborted due to " the upper triangular matrix element u(i,i) is exactly zero at i =2000, the factorization is completed but division by zero will occur if solution is attempted", what shall i do to overcome this error?

Asni

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• Nor,

The first message indicates that the primary variables are out of bounds during the Newton-Raphson iterations. The second message comes from the solver (are you trying to use the direct solver LUBAND?). Both messages indicate that something is setup very badly or wrong - but of course, I have no way of knowing what. I presume these error messages occur very early on, probably even at the very first iteration. If so, Set MOP(7)=9 and carefully check everything in the output file.

Stefan

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• Hi Stefan,

I've got another question. Can T2VOC run injection for remediation of surfactant, alcohol and water mixture? From what I read (from block GENER, keyword TYPE), T2VOC only got remediation which involve air, steam and water only. Is there any possibility I can apply remediation of surfactant, alcohol and water mixture?

Asni

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• Asni,

The first thing you would need to do is switch from T2VOC to TMVOC, as you have additional components. Then you would have to change the code a little to provide, for example, surface tension as a function of surfactant concentration (this change would be straightforward). Examine whether other properties of the fluids of interest (alcohol and surfactant) can be captured by the regular parameters you need to specify in the CHEMP block. Not sure I understand what you mean by "water mixture" (unless you mean mixtures of water and alcohol).

It may well be that somebody else in the TOUGH User Community has used TMVOC for this purpose and can give you much better advice.

Stefan

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