For modeling the topsoil cracks using MINC, what should be the number of continua? I think that two is fine, but is it?
How can I apply the fracture to a certain number of cells? My idea is to define a certain material type for those cells that have fractures in reality and give its fracture features to the fracture of this material. On the other hand, I assign the exactly similar material features to fractures and matrix for other (than that certain material) materials. Am I right?
(1) In MINC, you have a "fracture" continuum and a "matrix" continuum; you may subdivide the matrix continuum into multiple elements. Whether or not you want to further subdivide the matrix depends on how strong a gradient you expect in that continuum. Be also aware that as soon as you subdivide the matrix, a general dual-permeability approach (where global matrix-matrix connections are introduced) may not make sense.
(2) How to apply fractures "to a certain number of cells"? Not sure what you mean by that, but I assume you want to apply MINC to only a subset of all the elements of the primary mesh. To do that, recall that only active elements undergo the MINC processing, so you can rearrange the elements in block ELEME such that all elements belonging to the material(s) to be fractured are active, and the rest inactive (i.e., below the first element with a non-positive volume). Run MINC, then make all the elements in the secondary mesh (i.e., file MINC) active again.
I saw the example of MINC in TOUGH2 manual (problem #4). All the cells have fracture in that example, but I just want to have fracture in few of them. Do you mind looking at the input file that I had attached above and let me know how to make an input file that just a few of cells have fracture instead of all?
Thank you very much and happy new year!