Boundary condition on mesh

Sorry,

Your question too vague,

you can get the list of label of mesh3 Th

  int[int] labs = labels(Th); 
  cout << labs < endl; 

or you can build the surface mesh
load “msh3”
laid “medit”
Th = buildBdMesh(Th); // build the surface mesh
meshS Th1 = Th.Gamma;
plot(Th1,wait=1);
medit(“Th1”,Th1); // to see label of region of Th1 …