Anisotropic permeability modifier positions


I am a bit confused with MOMOP(20) option:

Is it correct that the only difference between setting it to 1 or 2 is the location of where the modifiers are read, but the internal usage is exactly the same?

So if setting MOMOP(20) to 1, I would have to provide data like this


  0 1          FRAC10.1000E+030.0000E+002.000000000.9500E+010.9500E+010.2000E+01          2.000000000.50000000
2 0 1          MATX10.1900E+040.0000E+001.000000000.9500E+010.9500E+010.2000E+01          3.000000002.50000000

and if if setting MOMOP(20) to 2 , it should look like this

  0 1          FRAC10.1000E+030.0000E+00          0.9500E+010.9500E+010.2000E+012.000000002.000000000.50000000
2 0 1          MATX10.1900E+040.0000E+00          0.9500E+010.9500E+010.2000E+011.000000003.000000002.50000000

Do I understand that right?


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  • Hi Julia,

    This is essentially correct. A few comments:

    (1) This is a new feature only available for iTOUGH2 7.1, which will be released later this year.

    (2) In iTOUGH2, permeability modifiers are specified as negative numbers; a positive value would indicate that permeability itself is specified. You used "large" positive values in your example. iTOUGH2 will then guess that you actually meant permeability modifiers rather than permeabilities, and make an internal conversion to a negative value; you will get a related warning message.

    (3) The difference between MOP2(20)=1 and MOP2(20)=2 is indeed minor. MOP2(20)=1 was introduced for the case where you already have specified isotropic permeability modifiers in Columns 41-50, and then want to add anisotropy. MOP2(20)=2 is easier to read, as all modifiers are together. Also check out the option to read anisotropic permeability modifiers from an external file using keyword MAPPI.


  • Hi Stefan,

    thanks for the details. I came across the MAPPI keyword, will take a deeper look if it is suitable for our application.


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