[ICEM] Cartesian for a simple channel, failure~~

lotus_blue · January 14, 2011, 11:09

hello

I am meshing a uniform square channel with ICEM.
The Cartesian method applied by the 'Femur' tutorial of ICEM CFD is used. Basically, I defined a Cartesian grid first and generated mesh based on this grid.
It looks straightforward...but I ended up with something like this~~~at the outlet of the channel...channel cartesian.png
Anyone has any idea?

la7low · January 14, 2011, 19:05

Dud you use blocking method? It looks like an O-grid at the channel end...

PSYMN · January 15, 2011, 15:22

Don't use BFCart, just use Hexa Blocking...

In this case, it looks like a projection problem.

lotus_blue · January 17, 2011, 15:16

I managed to get it done in 3 ways:
(1) Blocking->Save Unstruct Mesh; then Mesh-> Load from Blocking.
(2) Pre-Mesh; then Convert to Unstruct Mesh.
(3) Pre-Mesh; then Mesh-> Load from Blocking.

They all seem to generate the same results. In the tutorial, every time a mesh is generated, I need to go to the Mesh Tab, and click "Compute". But in this case, a mesh can be done without going to Mesh Tab~~~Could anyone say something about this?
And what is the mechanism behind the 3 different ways?

~~~~~~~~~~~~
And Simon, could you tell me what exactly is the "projection problem"?

Thanks for all your replies.

PSYMN · January 17, 2011, 16:32

1) The first half creates a UNS file from the loaded and computed blocking file and saves that uns file. The second half extracts an unstructured mesh from the loaded and computed blocking file. I never do it this way... Actually these are two different things... If you did the first half, you don't need the second half, you could just load the uns mesh file.

2) This converts the loaded and computed blocking file into an unstructured mesh file, saves it as hex.uns and loads it into the mesh editor... This is what I usually do.

3) This works too, similar to 2). Consider it a redundancy...

By projection problem, I mean it looks like the mesh in your last picture is not projecting to the end of the box... Is there a surface where it projected to or did it just start there and not project, I can't tell from here. I can only see that there is a problem.

lotus_blue · January 18, 2011, 14:15

It is a square channel. All the curves are associated with the edges of the blocking. The mesh was supposed to project to the end of the box, but it didn't. Don't know why it didn't work...Any ideas?

la7low · January 18, 2011, 14:30

Project face to surface yourself. Maybe that helps...

lotus_blue · January 18, 2011, 14:44

Quote:

Originally Posted by la7low

Project face to surface yourself. Maybe that helps...

thanks.

January 14, 2011, 11:09	Cartesian for a simple channel, failure~~	#1
lotus_blue New Member Join Date: Oct 2010 Posts: 8 Rep Power: 15	hello I am meshing a uniform square channel with ICEM. The Cartesian method applied by the 'Femur' tutorial of ICEM CFD is used. Basically, I defined a Cartesian grid first and generated mesh based on this grid. It looks straightforward...but I ended up with something like this~~~at the outlet of the channel...channel cartesian.png Anyone has any idea?

January 17, 2011, 16:32	redundancy...	#5
PSYMN Senior Member Simon Pereira Join Date: Mar 2009 Location: Ann Arbor, MI Posts: 2,663 Blog Entries: 1 Rep Power: 47	1) The first half creates a UNS file from the loaded and computed blocking file and saves that uns file. The second half extracts an unstructured mesh from the loaded and computed blocking file. I never do it this way... Actually these are two different things... If you did the first half, you don't need the second half, you could just load the uns mesh file. 2) This converts the loaded and computed blocking file into an unstructured mesh file, saves it as hex.uns and loads it into the mesh editor... This is what I usually do. 3) This works too, similar to 2). Consider it a redundancy... By projection problem, I mean it looks like the mesh in your last picture is not projecting to the end of the box... Is there a surface where it projected to or did it just start there and not project, I can't tell from here. I can only see that there is a problem.

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January 14, 2011, 19:05		#2
la7low Member Join Date: May 2010 Posts: 44 Rep Power: 15	Dud you use blocking method? It looks like an O-grid at the channel end...

January 15, 2011, 15:22		#3
PSYMN Senior Member Simon Pereira Join Date: Mar 2009 Location: Ann Arbor, MI Posts: 2,663 Blog Entries: 1 Rep Power: 47	Don't use BFCart, just use Hexa Blocking... In this case, it looks like a projection problem.

January 17, 2011, 15:16		#4
lotus_blue New Member Join Date: Oct 2010 Posts: 8 Rep Power: 15	I managed to get it done in 3 ways: (1) Blocking->Save Unstruct Mesh; then Mesh-> Load from Blocking. (2) Pre-Mesh; then Convert to Unstruct Mesh. (3) Pre-Mesh; then Mesh-> Load from Blocking. They all seem to generate the same results. In the tutorial, every time a mesh is generated, I need to go to the Mesh Tab, and click "Compute". But in this case, a mesh can be done without going to Mesh Tab~~~Could anyone say something about this? And what is the mechanism behind the 3 different ways? ~~~~~~~~~~~~ And Simon, could you tell me what exactly is the "projection problem"? Thanks for all your replies.

January 18, 2011, 14:15		#6
lotus_blue New Member Join Date: Oct 2010 Posts: 8 Rep Power: 15	It is a square channel. All the curves are associated with the edges of the blocking. The mesh was supposed to project to the end of the box, but it didn't. Don't know why it didn't work...Any ideas?

January 18, 2011, 14:30		#7
la7low Member Join Date: May 2010 Posts: 44 Rep Power: 15	Project face to surface yourself. Maybe that helps...