Gmsh - structured mesh around a sphere

Iuvatix · February 7, 2022, 10:25

Hello,

I want to build a structured mesh around a sphere for numerical simulations using OpenFoam. There I want to compare the stability of the solvers for unstructured and structured grids. The surface mesh around the sphere should look like https://catlikecoding.com/unity/tuto...ho-frontal.png.

I thought I could use Gmsh since it is free and I heard it is quite good, but I am not experienced with Gmsh. I wanted to start defining the 6 surfaces on the sphere, but could not split the curves.

Can someone help me with my approach or has a better way of doing it?

Greetings
Florian

Ship Designer · February 9, 2022, 18:41

Have you checked the sphere OpenFOAM tutorial in tutorials/mesh/blockMesh/sphere and sphere7 ? I think it should point you in the right direction otherwise I suggest looking into blockMesh's capability of projecting block faces onto surfaces. It's very powerful and you can get very good quality grids but it's very tedious to set up. Good luck!

Iuvatix · February 14, 2022, 04:33

Thank you for the advice. I am currently looking into it and it seems very helpful. Can I somehow specify that I don't want a mesh inside the sphere (or another volume)?

Ship Designer · February 14, 2022, 05:13

If you want to model the domain around the sphere, you would have to subdivide the domain in an appropriate number and topology of blocks and then project the faces onto the sphere from the outside towards the sphere. In order to reduce the amount of work you could then use the mirrorMesh utility to mirror the grid around a plane of symmetry, in case you need the full sphere.

At the bottom of this page you can find an example of such a topology.

February 7, 2022, 10:25	Gmsh - structured mesh around a sphere	#1
Iuvatix New Member Florian Join Date: May 2021 Posts: 8 Rep Power: 4	Hello, I want to build a structured mesh around a sphere for numerical simulations using OpenFoam. There I want to compare the stability of the solvers for unstructured and structured grids. The surface mesh around the sphere should look like https://catlikecoding.com/unity/tuto...ho-frontal.png. I thought I could use Gmsh since it is free and I heard it is quite good, but I am not experienced with Gmsh. I wanted to start defining the 6 surfaces on the sphere, but could not split the curves. Can someone help me with my approach or has a better way of doing it? Greetings Florian

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February 9, 2022, 18:41		#2
Ship Designer Senior Member Claudio Boezio Join Date: May 2020 Location: Europe Posts: 137 Rep Power: 6	Have you checked the sphere OpenFOAM tutorial in tutorials/mesh/blockMesh/sphere and sphere7 ? I think it should point you in the right direction otherwise I suggest looking into blockMesh's capability of projecting block faces onto surfaces. It's very powerful and you can get very good quality grids but it's very tedious to set up. Good luck!

February 14, 2022, 04:33		#3
Iuvatix New Member Florian Join Date: May 2021 Posts: 8 Rep Power: 4	Thank you for the advice. I am currently looking into it and it seems very helpful. Can I somehow specify that I don't want a mesh inside the sphere (or another volume)?

February 14, 2022, 05:13		#4
Ship Designer Senior Member Claudio Boezio Join Date: May 2020 Location: Europe Posts: 137 Rep Power: 6	If you want to model the domain around the sphere, you would have to subdivide the domain in an appropriate number and topology of blocks and then project the faces onto the sphere from the outside towards the sphere. In order to reduce the amount of work you could then use the mirrorMesh utility to mirror the grid around a plane of symmetry, in case you need the full sphere. At the bottom of this page you can find an example of such a topology.