[Akinna]

Hello,

I've been working to solve this problem for some days now, but I can't get a solution. Also the posts in forums and google search do not help.

I try to mesh a channel with a concave surface (see attached pictures). It seems like snappyHexMesh is doing the first snapping step, but not the snapping to the surface. I already tried to increase the number of cells in my background mesh and the refinement level. Also I tried to increase and decrease the number of maximum local and global number of cells but nothing helps.
SnappyHexMesh meshes the same channel with a non concave surface (a rectangular channel) with the same meshing options quite well.

Do you have any suggestions or ideas where my mistake is?

Thanks in advance for any input!

Akinna

STL_ConcaveSurface.jpg

Mesh_ConcaveSurface.jpg

blockMeshDict.txt

snappyHexMeshDict.txt

[Akinna]

Hey,

I tried to mesh only half of the channel with the same mesh settings and here snappyHexMesh is snapping quite well (see Image below).

Mesh_HalfDomain.jpg

Half of the channel means, that the Geometry is 16m long and 0.14m wide (the whole channel is 32m long). Any ideas what is going wrong while meshing the long channel?

Greetings
Akinna

[Laika]

Hello Akinna,

I have no idea why you obtain these results from sHM, but if you can share your stl or obj file, I'd like to investigate this with you. I'll be doing something with long channels in the near future, and hence may run into the same problem as you have...

cheers,
Laika,
still orbiting

[Akinna]

Hey Laika,

I am sorry for the late reply, but I am not allowed to share the STL-Files. I am still working to solve the problem. Gonna let you know when I find a solution.

Cheers
Akinna

[Akinna]

Hey,

I found a solution here:

http://www.cfd-online.com/Forums/ope...pped-mesh.html

I turned down the nsolveIter to 30 and now the mesh looks quite good.

Cheers
Akinna

[KarenRei]

Originally Posted by Akinna

Hey,

I tried to mesh only half of the channel with the same mesh settings and here snappyHexMesh is snapping quite well (see Image below).

Attachment 50717

Half of the channel means, that the Geometry is 16m long and 0.14m wide (the whole channel is 32m long). Any ideas what is going wrong while meshing the long channel?

Greetings
Akinna

Based on recent (albeit very limited) experience: by reducing the geometry to half but keeping all meshing settings the same, you're effectively doubling the number of max cells for the mesher to use per unit volume. Just a thought!

[Akinna]

Hey KarenRei,

thanks for your answer. Yes this was also my first thought but increasing the max number of cells didn't help.

Cheers
Annika