Well, we have tried to do this using the crystal plasticity finite element method. This is not the perfect way, but still you can get some grain size distributions.
But we were using our in-house codes running in Wolfram Mathematica and AceGen/AceFEM. You can also check the literature overview there for other approaches.
Article Grain refinement in the ECAP process: simulations using the ...
U can go though this link which I have mentioned below. u can get some idea how to measure the grain size.You can use Imagej software to identify the grain size.https://youtu.be/YPQsCjHzWg4
It is impossible to answer this question unequivocally. Yes, there are attempts to create the right software. But they are based on the study of data structures of materials deformed by a given method.
The degree of fragmentation is closely related to the deformation method, the larger the theory, the smaller the grain. The temperature and the rate of deformation are also important. And the material itself. One will be deformed by slipping, and the other will be twins. And also the tendency to produce the substructure.
As you can see, the factors responsible for the finegrained are many. Therefore, there is no right answer. Only the experiment will tell you what you have received.