[Nk.aguirre]

Hi,

I woud like to simulate the electric field of hollow torus. I use the following text:

SetFactory ("OpenCASCADE");
Torus (1) = {0,0,0, 201,50, Pi};
Torus (2) = {0,0,0, 158,34, Pi};
BooleanDifference (8) = {Volume {1}; Delete; } {Volume {2}; Delete; };

In some examples, the author puts the instructions: physical volume, physical surface, or surface loop. In this case, is it not necessary to take any of these? why is it necessary to include these instruction?. Is there a program to improve meshing such as bandwidth?

thanks