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-   -   [ICEM] Blocking strategy for a Multi Element Airfoil (ICEM) (http://www.cfd-online.com/Forums/ansys-meshing/114008-blocking-strategy-multi-element-airfoil-icem.html)

mix March 3, 2013 13:38

Blocking strategy for a Multi Element Airfoil (ICEM)
 
Hey everyone,

for some days now I'm working on a blocking strategy for a multi-element airfoil in ICEM. My plan is to use a CHgrid. I've alredy meshed the single-element one porperly, but now I'm stuck. Unfortunately, I also could not find any tutorials or proper papers regarding multi-element airfoil meshing.
My plan was to use one Ogrid Block in combination with the rearmost edge of the farfield for each element to create the Cgrid. But that does not work as intended.
Now I was hoping, you guys could give some ideas and new thoughts on the topic. I'm not exactly explaining, how I was trying to mesh the geometry, so I eventually can get some new suggestions.

Here a screenshot of the airfoil:
http://imageshack.us/photo/my-images/534/airfoilm.jpg/


mix

mix March 4, 2013 09:53

After working a few more hours, I've achieved some results, but also an error.
I want so split a vertex, but ICEM only gives me the error "unusual neigborhood" (see the image attached). Does anybody know this error or how to solve it? Unfortunately, I could not find a solution for this.

http://img546.imageshack.us/img546/1...eigborhood.jpg

diamondx March 4, 2013 11:27

not many times, the split vertex has worked well for me. before using it, why don't you click on previous and jump where your merge those vertex. see why you needed to merged them... may be you didn't have to.

mix March 4, 2013 11:44

Sorry for asking, but what exactly do you mean with "click on previous"? I haven't recognized this option yet. Or do you simply mean "undo"?

diamondx March 4, 2013 11:45

sorry, i meant undo nothing magical here

mix March 4, 2013 11:49

Alright.
The Problem is, I saved several times in between, so I can't undo to that specific point. I probably will built up the model once again to work around the problem.

diamondx March 4, 2013 11:52

when you save, icem does not replace your blocking, he keeps a backup of it. and keep just the last one. go to your folder you will find a lot of file with the extension blk0,blk1,bl2. those are backups of your blocking, just change the extension to blk and it will work again.

mix March 5, 2013 05:32

I produced some results I want to shear.
I am aware, that there ist quite much skewness, especially at the slat between the airfoils. My blocking strategy was to first generate the cgrid for the main airfoil and afterwards the one for the flap, so I could fit one to the other.
Feedback and tips for improving the mesh would be awesome.

Mesh:
http://imageshack.us/photo/my-images...turedmesh.jpg/

Slat:
http://imageshack.us/photo/my-images/805/slat.jpg/

Blocking:
http://imageshack.us/photo/my-images/708/blocking.jpg/

Far March 5, 2013 08:26

Blocking is not great... Quarter O-grid is necessary...

mix March 5, 2013 08:47

Hey Far,

could you explain what you mean with "Quarter O-grid" a bit mor in detail? I'm just learning to use ICEM and I'm not familiar with all the options/possiblities.

Far March 5, 2013 08:57

http://www.cfd-online.com/Forums/ans...ler-blade.html

mix March 5, 2013 09:02

Thanks!
I will try this one on my model. If requested, I will post my results, as they are done.

mix March 5, 2013 13:46

Far, I assume you mean something like this:

http://img819.imageshack.us/img819/6...arterogrid.jpg

For now, just for the main airfoil and no mesh refinement ore anything like that is done. It will get interesting to adopt it for the flap.

-----

First attempt with meshed flap:

http://img138.imageshack.us/img138/2...rogridflap.jpg

mix March 7, 2013 05:46

Sorry for another double post, but I do need some more help with this one.
As I can not find any proper sources for multi element airfoil hex meshing, some ideas, especially with the blocking of the flap, would be extremely helpful.
My way until now was to first block the main element and after finishing this one, splitting blocks to generate a mesh for the flap. My problem now is, that in this way many small linked blocks appear which I don't know how to deal with properly. I don't thing merge blocks is the way to go, as I tried this option which did not result in a proper mesh.

diamondx March 7, 2013 11:23

did you see this thread : http://www.cfd-online.com/Forums/ans...ic-trough.html

it might help you...

mix March 7, 2013 12:33

I did see this thread and I even built up the blocking for the main element as discribed there. The problem is the flap.
As I described, blocking it leads to several little linked blocks, as I blocked the main element first and then splitted the blocks to fit the flap.


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