Hello,
Again, this all depends on the resolution of the grains that you are willing to live with. The physical size of the model does not really matter. Let me explain a bit.
If your cylinders are 1cm in diameter and 8 cm in height that could be modeled with a voxel grid that is simply 1 voxel in the X and Y axis and 8 in the Z Axis. But clearly this would not really make sense to get any good data but does give us a starting point.
Let us now increase this size of the voxel grid by 10 in each direction: 10 x 10 x 80. That is 8000 voxels. Getting better but probably still not nearly enough fidelity in the model to show the open cell foam with much detail.
Let us now increase another 10x: 100 x 100 x 800. That is 8 million voxels. Still just fine on memory but maybe starting to get up there for Ansys Desktop. But now we can start talking about how well represented the foam would be. That puts the spacing at 0.1 mm (100 microns) per voxel. As a rule of thumb you would probably want about 5 voxels across the diameter of a foam “ligament” which means your foam ligaments need to be 500 microns in diameter. I have no idea if this meets your expectations or not.
If you are trying to model something like a 1 micron ligament diameter then you will either need to go to a super computer that runs Ansys or cut down the physical size of your model.
I am also assuming that Ansys is going to import the model as a hexahedron mesh. You could create a triangular surface mesh with DREAM.3D and then have Ansys generate a volume mesh from that but not sure I would recommend that path.
Hop this helps you figure out how to model your foam.