Development of an MSH import tool

[nikoscham]

Overview

This thread will monitor the development of a new tool for importing MSH files (created by Gmsh)

Tasks

• Import of 2D mesh with quadrilateral elements
• Import of 2D mesh triangular elements
• Handle boundary conditions import from GMSH to FEAScript
• Update nodal numbering process for 2D meshes with triangular elements
• Update boundary conditions for 2D meshes with triangular elements
• Create new tutorials with quadrilateral and triangular meshes

[nikoscham]

Want a clarification whether that is the best mesh format for FEA.

Originally posted by @sridhar-mani in #10

@sridhar-mani are you working on tetrahedral 3D cells? 3D cases are not yet implemented on FEAScript. It's on the future plans for sure. I think it would be better to start with simpler 2D quadrilateral cells. In addition, quadrilateral cells are generally more accurate compared to triangular (both are 2D cases). Triangular however are useful in the case of a complex geometry. I have made a similar module in the past for a Fortran FEM code. See the e.g. the readmeshEL function in https://github.com/nikoscham/DropS/blob/main/Source/coord.f90, where I import 2D meshes either from Gmsh or from Triangle. I think it may be helpful.

[sridhar-mani]

I have implemented a 2d quad cell reader for now from .msh v4.1 file. I am looking more into the format as i had previously worked on openfoam meshing and not used to this. Also want a confirmation if the current output is good to go with the sim.

Update - Have now implement the reader to read both quad and triangle comprising gmsh file.

[nikoscham]

I have implemented a 2d quad cell reader for now from .msh v4.1 file. I am looking more into the format as i had previously worked on openfoam meshing and not used to this. Also want a confirmation if the current output is good to go with the sim.

Update - Have now implement the reader to read both quad and triangle comprising gmsh file.

Thanks for the update and for all the work on this! Give me some time to perform some tests

[nikoscham]

I have created the following mesh (both triangular and quadrilateral mesh versions) in Gmsh for testing purposes.

rect_mesh.zip

[sridhar-mani]

I have created the following mesh (both triangular and quadrilateral mesh versions) in Gmsh for testing purposes.

rect_mesh.zip

BTW - Also made a gpu branch where fully webgpu offloading has been implemented. Implement more precise reading of both triangle and quadrilateral elements from the .msh file.

Doubt - What format do you want the final output mesh to be if i include reading the boundary conditions.

[sridhar-mani]

is the mesh reading is as per the needed format and what next to develop?

[nikoscham]

is the mesh reading is as per the needed format and what next to develop?

I am building a gmsh example here: https://github.com/FEAScript/FEAScript-core/blob/main/examples/solidHeatTransferScript/HeatConduction2DFin/HeatConduction2DFinGmsh.html
I'll need a bit of time to go through your mesh import code. Sorry for the delay. Thanks again for all the contributions!