Physical number in 3D msh

why comes this error?I use Gmsh to create the msh,but always lead to this error.Thank you!

HI @senzhao

Thanks for trying the software. Every volume should have be assigned to a physical group. My understanding is that gmsh should automatically remove mesh elements that do not have a physical group assignment.


Please avoid the number 0 for a physical group assignment.

Thank you for your reply.I tried to build one cylinder and it fits well in physical number(show no problems),but two cylinders show the same problem in physical number.
P.S. thank you for your advice.I will try to see if it can work.

Hello @senzhao

Here is an example for a cylinder within a cylinder using pygmsh with boolean operations.

There is a script in the same directory that handles adding the interface and contact boundary conditions: