u/TimelyPhrase3592

I have been using COMSOL Multiphysics 6.4 to do the meshing of complicated STLs of Porous materials.
Here is the pipeline I am using
I have got the tomography scans
So I segment them into 4 different phases using Avizo 3D
Then I generate the STL file using FIJI
Finally I load them into COMSOL
However, every time I am stuck with the same error that the faces are overlapping or something like this. I have tried numerous ways like reducing the volume of element size, cleaning using software called Meshlab, deleted the flagged faces, but nothing seems to work.

It will really be a great help if someone could suggest a way out of this mess ; )