CFD Online Discussion Forums

CFD Online Discussion Forums (http://www.cfd-online.com/Forums/)
-   ANSYS Meshing & Geometry (http://www.cfd-online.com/Forums/ansys-meshing/)
-   -   [ICEM] Prism mesh problems (http://www.cfd-online.com/Forums/ansys-meshing/72375-prism-mesh-problems.html)

camilo_costa February 3, 2010 13:23

Prism mesh problems
 
1 Attachment(s)
Dear Friends.

When i extrude a prism mesh on the two orthogonal surfaces with three layers, the second and thirth prism mesh layer on the corner of this surfaces don't have been extruded that result in only one layer in this region, compromising the quality of the mesh. Fig below show the problem.

PSYMN February 4, 2010 11:20

Curves are trapping Prism out of the corner
 
I can't see it in the picture, but I am betting that you have curves coming out from that corner horizontally to the left and vertically to the top. These curves are more the edge of surface patches and don't actually represent special features in your model.

When you generate a tetra mesh on that, it assumes the curves are important to you and makes sure that the tetra nodes respect them (associate to curve with green nodes). These curve associated nodes must slide on the curves. You can see these green nodes by right clicking on Mesh in the Display tree and turning on the options for “as dots”. But in your image, I can at least see that all your nodes are precisely aligned.

Next ICEM CFD tries to insert prism layers. This command would like to slide the tetra mesh outward from the hole (at 45 degrees), but the node at the corner is on two diverging curves... If it follows either one, you get very poor quality (180 degrees at the corner), so it gets stuck and can't be slid out. This stops prism locally and results in a stair step prism away from the corner.

To fix this problem, delete those unnecessary curves (make them dormant). The Build Diagnostic Topology with Filter Curves and Points by an angle will do it automatically for you. If the mesh is large/complicated and you don't want to regenerate it, you can just project those nodes to surface (under move nodes), and also delete the line elements in this area.

camilo_costa February 4, 2010 12:55

Problems with lines?
 
I am already doing a Build Topology wheen i maked my mesh. And the lines that are not associate with the surfaces was deleted.

PSYMN February 5, 2010 01:27

Hmm?
 
Are you saying you do not have curves running out from that corner along the purple surface? Are you saying that when you display nodes as dots you do not see green nodes on that purple surface?

I was pretty sure that was it, but maybe take a few more screen shots of the geometry, etc. will give me more clues.

If you wanted to post the model its self (or send it to me privately) I could take a quick look.

Simon

camilo_costa February 8, 2010 10:50

tim file
 
1 Attachment(s)
If was possible to analize my (.tin) file, i was very grateful.

The surface that with prism mesh problems are: VENT and PAR_EST in the corners that showed in the fig zipped.

THX!!

camilo_costa February 8, 2010 10:52

figs
 
1 Attachment(s)
figs below

PSYMN February 9, 2010 09:57

Wrong file.
 
I went to take a quick look, but the zip file just has an image in it. Please try again with the Tetin file.

Simon


All times are GMT -4. The time now is 01:36.