Tetrahedrons 16 or 17?

[selopez]

According to the Theory Guide, tetrahedra 16 allow more acurate results than the 17 ones. The guide explains convincingly the difference in stiffness between them. While NetGen seems to be more consistent than TetGen, I have been able to obtain well-refined tetrahedra 16 meshes in most of the models I tested. However, the task becomes a nightmare when selecting nodes for the application of the bounday conditions. Not only for the number of nodes but also because the meshes generated by TetGen are somewhat irregulars. Have you any comment to make on this issue?

[auroraIco]

Creating the perfect mesh is a philosophic matter. Of course you are right 10 nodes tetrahedron are more precise than 4 nodes ones because of the different shape function. But if you use a finer Nr. 17 mesh the results should be equal to a coarse Nr. 16´s one. Our tests show that a tetgen mesh looks a kind of crude but the result quality is very good. Netgen meshes always look fine but sometimes especially in models with many curvatures the mesh hasn´t the desired quality. Don´t believe only your eyes! Best way to check your results is to do a couple of analysis and compare them for relevant parts.

Best wishes
Aurora_ico

[selopez]

Thank you very much. Your comments are realistic and helpful. Regards.

[auroraIco]

You´re welcome!