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-   -   [ICEM] O-grid around wing geometry (http://www.cfd-online.com/Forums/ansys-meshing/68656-o-grid-around-wing-geometry.html)

 Anorky September 28, 2009 05:40

O-grid around wing geometry

5 Attachment(s)
Hi everyone,

I am currently scripting a geometry construction and mesh generation in ICEM.

I want to construct a fully structured O-grid around a 3D wing geometry. An illustration of my geometry can be found in the attached figures.

Since I will mesh several types of airfoils and different "wing shapes" I want the blocking to be automatic. By different wing shapes I mean the cornering (arc or ellipse form) and dimensions.

Therefore I was planning to use the 2D surface blocking function to create the surface blocking and than extrude this 2D blocking to a 3D blocking.

I have tried and used this option for a more simple geometry and that worked fine.

However for this geometry I haven't had any succes obtaining a good blocking.

To create the fully structured (boundary layer) O-grid around the wing, I constructed a boundary layer geometry around the wing. The idea is to block the fluid region in between the outer, boundary layer geometry, and the inner wing geomerty.

Now I do the following steps:
1) open the geomerty, (wing geomerty, boundary layer geomerty; both are connected in the symmerty plane by surfaces, see the figures)
2) 2D surface blocking with following settings: Method: Mostly mapped; merge mapped blocks is off; 2D Free block mesh type is all quads; Selected surfaces: All
3)2D to 3D; O-grid option is off, simple fill is off.

What I don't understand is why ICEM creates 3 split block for the outer rear symmetry surface. Resulting in also 3 blocks for the "triangular region" between the trailing edge. I can imagine that this "triangular region might cause some problems. I included a figure that will make the above more clear.

Has anyone a suggestion how to achieve a clean blocking?
Another solution would be to start with a 3D bounding block and split this block manually and associate the relevant vertices and edges to the geometry. However this would be to complex to script for my problem since the number of cornering section, and corner shape (arc or ellipse,...) will change often. I think this solution wouldn't be that flexible to implement in my script code as the 2D surface blocking method would be.

I might have made a fundamental mistake from the beginning on but for this moment I am out of ideas for valid solutions so I hope someone can help me.

Any ideas or suggestions are welcome. If something is not clear, please don't hesitate to contact me!

kind regards

 PSYMN October 12, 2009 15:37

Try blocking it yourself...

Yea, I would say the 2D blocking has not been ideal for this configuration, particularly with that lower block... It just sees the angles on that surface as too great to assume you want them mapped.

I would use scripting to record the interactive steps to generate an ideal 2D blocking.

I may be able to help with that if you want to send me what you have...

 Anorky November 2, 2009 05:55

Hi Psymn,

Sorry for my late response, I haven't checked the forum for a while.

It seems I solved to problem by doing the blocking in 2 stages.
I create a 2D surface blocking for the front parts. The degenerate blocks near the trailing edge are made manually.
Then I merge both blockings yielding the final blocking.

This seems to work :)

Regards

 PSYMN November 3, 2009 18:42

fully scripted...

Great, but just for the record, a fully scripted solution is possible. Let me know if want to try for that.

Simon

 Anorky November 5, 2009 11:15

Hi Simon,

I have wrote a script that does the trick automated.

I am trying to write scripts for the complete mesh and geometry creation.
The geometry is created by use of several input parameters. Afterwards the whole blocking process and mesh generation are done by use of scripts.
In the end this should allow the whole mesh and geometry creation to be fully automated. This will be very usefull for me since I want to try several different configurations.

When I started the scripting process I hoped it to be easier than it is :)
I find it relative difficult to find a good scripting reference/ manual.

The replay function works fine altough a lot of unnecessary lines are recorded as well in my point of view. But it works fine to find the correct commands and arguments.

Do you have good reference material concerning the tcl/tk commands in icem despite the provided manual?

thanks for replying on my post!

Kind regards

 PSYMN November 16, 2009 21:22

Programmers Guide?

Did you already find the programmers guide under "help"?

You could also go to "scriptics.com"

 Anorky November 17, 2009 05:15

Hi Simon,

Indeed, I already know the programmers guide. The scriptics website I found a while ago but has been under reconstruction since than...
Thanks for the suggestions and if you would know other reference material it would be more than welcome :)

kind regards and thanks for replying on my posts!

 Crazy CFD November 18, 2009 07:26

3D Iced Wing Meshing

Dear All of Friends!
I am currently trying to generate the 3D Iced swept wing mesh generating in Gridgen V 15.
First, I really thanks all of you for reading my wirtting.
I want to generate a multi-block Hybrid mesh or Fully Structured C-grid around the 3D Iced swept wing geometry.

Has anyone a suggestion how to creat a hybrid or sturctured multiblock grid around the iced wing geometry?
I hope someone can help me that problems.
welcome!!!
Thank !!
Crazy CFD

 PSYMN November 18, 2009 11:16

Sell crazy some place else

5 Attachment(s)
What? Are you Crazy ;)

This forum is mainly for ANSYS brand mesher (ICEM CFD Hexa, Gambit, TGrid, CFX Mesh, etc.), but there is another forum for Pointwise. You will probably find more Gridgen users there who can help you.

On the other hand, if you are interested in seeing how this would be done with ICEM CFD Hexa, I can help with that. :cool:

 jchawner November 21, 2009 11:02

Crazy:

As Simon says, join us crazy Pointwise people in the Main CFD Forum! Regardless, there are some very straight forward procedures for generating both hybrid and structured grids around wings and airfoils, iced or not. I would be interested in seeing the geometry first in order to get an idea of what we're talking about.

Simon: Thanks for pointing Crazy in our direction.

 aweizazuji August 14, 2011 03:10

Hi Simon, I just want to ask how you coud generate structure grid on the surface of the body(like in your attachment --the wing) and the generate unstructure grid in the field(like delaunary method)? thanks. I did this before , first i have structure mesh by blocking method, then change to mesh, but like in the symmetric surface ,when meshing it, even i use repect line element command, the nodes do not merge. thank you1

 PSYMN August 17, 2011 16:02

For those models (the nacel, the fan blade and the F6 aircraft), I just used the "MultiZone" method.

It is really ICEM CFD Hexa, but with an "unstructured" block to cover the difficult area around everything. It handles the connectivity, sweeping, delaunay, etc. all on its own.

There should be a couple new tutorials coming out with 14.0 in a few months, and one of them is a propeller shaft similar to that fan example.

 aweizazuji August 17, 2011 21:28

Thank you Simon, I am looking forward.

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