Coarse to fine transition of mesh

Altair Forum User

I came across this mesh image in the internet.

Can anyone explain how this is a valid mesh? Won't this result in connectivity issues in the mesh due to hanging nodes?

 

<?xml version="1.0" encoding="UTF-8"?>

Rahul Rajan_21763

Please check for what type analysis this mesh has been used.I am sure this mesh is not for structural analysis.

Altair Forum User

@Rahul R, I think it's for CFD.

https://meshing.lanl.gov/proj/ASCEM_Tank/images/gallery.html

 

Is this type of hanging node OK for CFD?

Q.Nguyen-Dai

Yeah, that's CFD's meshing and Hyperworks does not support this kind of meshing.

I'm sure that Numeca can do this mesh.

 

Rahul Rajan_21763

As mentioned above its a CFD mesh.(Octree hex mesh)

Octree approach is useful when you have a very poor cad and tricky surfaces. Use this approach when you do not want to spend more time cleaning cad model. On the other hand, advancing front requires less user input to generate a good mesh, but it does require good quality CAD surfaces and tricky surfaces sometimes don't mesh. You can refer wiki on how the Octree algorithm works.

http://en.wikipedia.org/wiki/Octree

 

The Octree based tet meshing introduced in version 13.0 is a faster and high quality alternative to the proven advancing front meshing algorithm, and can be used with more than just CFD applications. And due to the logic behind this scheme it provides a very nice BL transition.

It can be accessed through the 3D page  tetramesh or CFD tetramesh panel  Tetramesh parameters option. Please refer snapshot below:

<?xml version="1.0" encoding="UTF-8"?>

Q.Nguyen-Dai

@Rahul R: 'Octree based' meshing of Hypermesh CAN'T product CFD mesh as mentionned at screenshot of @SKGPrashanth. Hypermesh's octree based meshing is TET mesh in fact.

Rahul Rajan_21763

Yes i do agree.That was just for information.In above mentioned link it says Octree Hex.

M.karthickraja

Altair Forum User said:

As mentioned above its a CFD mesh.(Octree hex mesh)

Octree approach is useful when you have a very poor cad and tricky surfaces. Use this approach when you do not want to spend more time cleaning cad model. On the other hand, advancing front requires less user input to generate a good mesh, but it does require good quality CAD surfaces and tricky surfaces sometimes don't mesh. You can refer wiki on how the Octree algorithm works.

 

 

http://en.wikipedia.org/wiki/Octree

 

The Octree based tet meshing introduced in version 13.0 is a faster and high quality alternative to the proven advancing front meshing algorithm, and can be used with more than just CFD applications. And due to the logic behind this scheme it provides a very nice BL transition.

 

 

It can be accessed through the 3D page  tetramesh or CFD tetramesh panel  Tetramesh parameters option. Please refer snapshot below:

 

 

 

 

 

<?xml version="1.0" encoding="UTF-8"?>

 

M.karthickraja

pls explain the option 'PYRAMID TRANSITION RATO ' in tetramesh parameters panel.

Pranav Hari

Hi M.karthickraja

 

 

Pyramid Transition ratio defines the relative height of pyramid elements used for the transition from hexa elements in the boundary layer to the tetra elements in the core

 

Thanks