No tetrahedra in region 1 0
Hi, I am having trouble meshing this region. I have a three layered region in 2D as you can see in the attached code which I extrude and get a three layered 3D object. Now I have 3 volumes (labelled 14 , 15 , 16) but when I attempt to mesh them I receive "No tetrahedra in region 1 0". Could you please let me know what I am doing wrong?
Thank you in advance.test.geo