[ringtail]

Hi, everybody.

I want to generate a hybrid mesh which is comprised of hexahedra and quad-surface mesh. The computation domain is two dimension, and 2D hexahedra mesh is used in region near the wall. The left domain is filled of quad-surface mesh.

But, I just know how to generate the quad-surface mesh using surface-mesher for 2D compute domain. I don't know how to generate a hybird mesh in which near wall region is replaced by 2D hexahedra mesh.

Anyone could help me?
Thanks.

[BrolY]

Maybe I'm wrong, but for me, 2D hexahedral elements are quad elements.

Why don't you create a full Hexa mesh? If your model isn't too complicated, block it quickly and it would be easier I guess.

[ringtail]

Originally Posted by BrolY

Maybe I'm wrong, but for me, 2D hexahedral elements are quad elements.

Why don't you create a full Hexa mesh? If your model isn't too complicated, block it quickly and it would be easier I guess.

Actually, I have generated a full Hexa mesh. But, unstructured mesh is better for optimization.

[BrolY]

By unstructured mesh, do you mean Tetra mesh?
Otherwise, if it is your blocking that you have converted to an unstructured mesh, this is an Hexa mesh for me

Anyway, do you want to create an hybrid mesh with Tetra and hexa ?

[ringtail]

Originally Posted by BrolY

By unstructured mesh, do you mean Tetra mesh?
Otherwise, if it is your blocking that you have converted to an unstructured mesh, this is an Hexa mesh for me

Anyway, do you want to create an hybrid mesh with Tetra and hexa ?

When I say " structured mesh", I mean Hexa mesh. And unstructured mesh means Tri- or Quad- Surface mesh.

Indeed, I don't know how to generate hybrid mesh with unstructured and structured mesh...

[BrolY]

There is an exemple in the user manual:

Split your geometry in two parts. And create an interface where you have cut your geometry. Mesh your first part with Hexa and your second part with Tetra.
Import the two meshes into the same project.
If you look at your interface, you will see the two meshes on it : tetra and hexa.
You need to merge the two meshes in your interface. For that, use:
edit mesh -> merge nodes -> merge tolerance
For the nodes, select the part interface
For the tolerance, it depends on your model
Select "ignore projection"
Apply

If it is an interface between two fluid, delete the part interface.
Run a check mesh after it. You may have errors such as uncovered faces -> click on solve problems and add the elements to your fluid part.
You may also have errors like non manifold vertices. It means you must refine your hexa and tetra mesh in order to have the same number of nodes on each part of your interface, so all the tetra vertices will find hexa vertices. Got it? Otherwise, you can play on the tolerance. The more you will reduce it, the less non manifold vertices you will find. But I will recommand to create a good mesh on each part of your interface.

I hope it helps

[ringtail]

Originally Posted by BrolY

There is an exemple in the user manual:

Split your geometry in two parts. And create an interface where you have cut your geometry. Mesh your first part with Hexa and your second part with Tetra.
Import the two meshes into the same project.
If you look at your interface, you will see the two meshes on it : tetra and hexa.
You need to merge the two meshes in your interface. For that, use:
edit mesh -> merge nodes -> merge tolerance
For the nodes, select the part interface
For the tolerance, it depends on your model
Select "ignore projection"
Apply

If it is an interface between two fluid, delete the part interface.
Run a check mesh after it. You may have errors such as uncovered faces -> click on solve problems and add the elements to your fluid part.
You may also have errors like non manifold vertices. It means you must refine your hexa and tetra mesh in order to have the same number of nodes on each part of your interface, so all the tetra vertices will find hexa vertices. Got it? Otherwise, you can play on the tolerance. The more you will reduce it, the less non manifold vertices you will find. But I will recommand to create a good mesh on each part of your interface.

I hope it helps

I have read the example, but your explanation is helpful. I will have a try.
I think the difficulty may be that the geometry is a little complex, it's a high lift device.

Thank you

[sidspark12]

whenever v r talking about the hybrid mesh.........that means it is the combination of tetra and hex mesh for 3D geometry........and tri + quad for 2D geometry.........here you are talking about quad + hex , so i think this is not the hybrid mesh case.........hex mesh in 2D is called as quad mesh...........

[sidspark12]

one more thing......if the geometry is simple.......then go for hex mesh...........but if it is complex then that time u have to do the hybrid meshing.........devide the geometry in no. of volumes according to ur convenience and then go for mesh.........may b this ll give u better result with less memory uses...........

[ringtail]

Originally Posted by sidspark12

whenever v r talking about the hybrid mesh.........that means it is the combination of tetra and hex mesh for 3D geometry........and tri + quad for 2D geometry.........here you are talking about quad + hex , so i think this is not the hybrid mesh case.........hex mesh in 2D is called as quad mesh...........

I dont think so...
When I said quad mesh, actually, I mean the mesh generated through mesh->compute mesh->surface mesh.
And hex mesh is the one generated by blocking.

What's more, the mesh is 2D.

[sidspark12]

hello ringtail......yes u r exactly right.........now when i translate this mesh in perpendicular direction to 2d mesh.....that will be the 3d mesh and that will be hex mesh......

[PSYMN]

Wow, this is a confusing thread...

I still have no idea what you want

Are you all set now?

[vmlxb6]

@ Broly: I got stuck in the first step itself. How do you split your geometry. Do you have to build a separate geometry ??

@ Simon: could you please help me with this thread

http://www.cfd-online.com/Forums/ans...brid-mesh.html

Its a pretty simple geometry but am unable to do it.

Thank you. Appreciate your help.

[BrolY]

Geometry -> Create/modify Surface -> Segment / Trim Surface
You should try to play with those options to learn how they work.
Good luck !