I just started using gmsh for 2D triangulations and I'm observing that both the nodes and elements are being outputted in ascending order (consecutively). This is good as it makes reading the data easier but I want to know if this is always the case.
Secondly, I also observed that the physical-line boundaries are outputted as elements with two nodes (line-elements in a 2D triangular mesh). I have also figured out that the actual elements (triangles) are listed after these line-elements. This then means that the true number of triangles (elements) in the mesh is the number of elements oputputted in the mesh file less the number of line-elements. Kindly let me know if this is the correct idea.
Thanks in anticipation.
I does not use gmsh. But for a cgns mesh, the elements and nodes are usually outputted in ascending order. For the inner elements(triangles) and boundary elements(line-element), we usually list the inner elements ahead of the boundary elements, to easier reading; however, the cgns form allows one to firstly list the boundary element. You should check whether this type of mesh can be correctly read by your solver.
As far as I am concerned, GMSH begins with the external nodes, then fills in the external boundaries. And after begins the fill in of the internal nodes. The order I have recognized is the following: From bottom to up, from left to right.
Hope it helps.
I have the same situation. I filtered out my quadratic tetrahedral elements with identical id out in Gmsh output file . in element section second coloumn should have diff iDs for diff elements. i.e ''11' for my case . you will have different one. Just filter them out and still you will have same geometry but similar type of element. And yes they are in ascending order.
Raj you define the mesh characteristics size when defining the coordinates for example.
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