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-   -   [ICEM] 3d blade mesh problems (http://www.cfd-online.com/Forums/ansys-meshing/89820-3d-blade-mesh-problems.html)

papis June 22, 2011 19:52

3d blade mesh problems
 
Hi all

I am trying to create a 3d grid of a blade with flat tips. I have been making 2d grids so I am not new with the blocking strategy but in 3d things get rather complicated. I end up with low quality mesh.I am sure that I am doing something in my blocking stategy.

I have links of the steps I make my meshing procedure so it's easier to point out what is wrong.

Thanks in advance.

1.The farfield and theblade(http://147.102.42.169/3dgrid/1.png)
2.Created the 3D Bounding box associated the edges and made an O-grid split
using the faces at the outflow and those "pointing" in the flat tips of the blade.(http://147.102.42.169/3dgrid/2.png)
3.I split in the "X" and "Z" direction to embrace the blade with a block
(http://147.102.42.169/3dgrid/3.png)
(http://147.102.42.169/3dgrid/4.png)

4. I delete the block embracing the blade an make edge association to match the blade boundaries
(http://147.102.42.169/3dgrid/5.png)

5.The problems start here,because i have to collapse the "trailing edge" blocks.
(http://147.102.42.169/3dgrid/6.png)
(http://147.102.42.169/3dgrid/7.png)
(http://147.102.42.169/3dgrid/8.png)
6.The resulting block structure has this strange triangle-shaped block which produces very strange elements.(in the picture I have removed a layer of blocks)
(http://147.102.42.169/3dgrid/9.png)

I am sure that my blocking strategy is the problem.I would appreciate any ideas or thoughts.

Thanks again

jeevankumarb June 23, 2011 02:00

Hello papis,

Do not delete the block embracing the blade. Create c grid around the blade and extend it in both Z direction till the boundary. Then you collapse the tte wake blocks as you did and also the block inside the blade.

regards
Jeevan

papis June 23, 2011 05:29

Hi Jeevan,

Thanks for your reply.I am not sure I understand what you say. Whether or not I delete the block embracing the airfoil doesn't make any practical difference.After I collapse the trailing edge block these "wedge" shaped boxes appear(from the flat tip to the farfield,I can't collapse those because i will lose the flat tip boundary).

Take a look at the resulting blocks after collapsing the blocks of the trailing edge.

http://147.102.42.169/3dgrid/wedgeb.png

Thanks again for your time

jeevankumarb June 23, 2011 07:21

i am sorry it was my mistake in understanding the issue.
You can do one thing you can create Y-grid for the degenerated wedge shape blocks, this might improve the quality.

papis June 23, 2011 07:56

Yeah,you are right Y-grid conversion makes the quality better.

Thanks a lot


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