[hermes3d] Investigate Gmsh

[Zhonghua Ma]

Hi,

 

All the informatin were from the attached gmsh.pdf file.

 

Q1. Whether Gmsh can generate triangular, quadrilateral, and combined meshes in 2D, and curvilinear elements in 2D? What kind of meshes can be generated in 3D, and whether they can have curved elements?

 

Gmsh’s mesh module regroups several 1D, 2D and 3D meshing algorithms, all producing grids conforming in the sense of finite elements.

- The 2D unstructured algorithms generate triangles or both triangles and quadrangles. The 3D unstructured algorithms generate tetrahedra.

- The 2D structured algorithms (transfinite and extrusion) generate triangles by default, but quadrangles can be obtained by using the Recombine commands. The 3D structured algorithms generate tetrahedra, hexahedra, prisms and pyramids, depending on the type of the surface meshes they are based on.

 

All meshes can be subdivided to generate fully quadrangular or fully hexahedral meshes with the Mesh.SubdivisionAlgorihm option. However, beware that the quality of subdivided elements initially generated with an unstructured algorithm can be quite poor. (derives from page 49 of gmsh.pdf file)

 

Q2. Does Gmsh support NURBS curves/surfaces?

 

Yes, but only via STEP, IGES or BREP model import (not in Gmsh’s ‘.geo’ files). Gmsh has to be compiled with OpenCASCADE support for this to work. (derives from page 206 of gmsh.pdf file)  

Note that: STEP (Standard for the exchange of product model data), IGES (Initial graphics exchange specification) and BREP are standard data formats for CAD/CAM.