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Old   February 28, 2012, 16:53
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Hey there,

This is my first post on this forum.
I'm a fourth year student in engineering school in France and I have a project this year which consists in studying wingtip vortices with CFD.
I modeled several wingtips (with and without winglets) with CATIA V5 but I must say I'm having trouble meshing the geometry.
I came across this topic thanks to google and I must say, it looks like a great solution to deal with my problem : hexa structured meshing near the geometry and progressive tetra in the fluid volume.
I tried to follow the explanations posted a few weeks ago but there's no way I can get anything satisfactory...

I would really appreciate a more accurate tutorial describing the steps to follow in order to achieve this kind of mesh.

Thank you so much in advance.

Antoine
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Old   February 28, 2012, 17:33
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Salut Antoine,
tu remarquera qu'il n'y a pas d'accent dans mon message. Desole pour cela, mon clavier est actuellement anglais. J'ai depose dans mon fichier public un tuto ICEM CFD sur les aile d'avion. Voici le lien. Let me know quand tu l'aura telecharger pour que j 'efface. J'espere qu'il te viendras en aide. Cliques sur le lien ci-dessous:
http://dl.dropbox.com/u/35161486/ICE...body_Prism.pdf
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Old   February 28, 2012, 18:58
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Quote:
Originally Posted by diamondx View Post
Salut Antoine,
tu remarquera qu'il n'y a pas d'accent dans mon message. Desole pour cela, mon clavier est actuellement anglais. J'ai depose dans mon fichier public un tuto ICEM CFD sur les aile d'avion. Voici le lien. Let me know quand tu l'aura telecharger pour que j 'efface. J'espere qu'il te viendras en aide. Cliques sur le lien ci-dessous:
http://dl.dropbox.com/u/35161486/ICE...body_Prism.pdf
The prism method is different from Multizone method, I'm not sure which works better for FLUENT applications.
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Old   February 28, 2012, 19:01
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Quote:
Originally Posted by Winglet_CFD View Post
Hey there,

This is my first post on this forum.
I'm a fourth year student in engineering school in France and I have a project this year which consists in studying wingtip vortices with CFD.
I modeled several wingtips (with and without winglets) with CATIA V5 but I must say I'm having trouble meshing the geometry.
I came across this topic thanks to google and I must say, it looks like a great solution to deal with my problem : hexa structured meshing near the geometry and progressive tetra in the fluid volume.
I tried to follow the explanations posted a few weeks ago but there's no way I can get anything satisfactory...

I would really appreciate a more accurate tutorial describing the steps to follow in order to achieve this kind of mesh.

Thank you so much in advance.

Antoine
See my previous reply, I found the problem might caused by the wedge shape on the tip of the airfoil.
The method posted by Simon work fine with simple geometries.
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Old   February 28, 2012, 19:31
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@Diamondx : Merci pour ta réponse, j'ai téléchargé le fichier, tu peux le supprimer. Je lirai le tuto demain et je verrai ce que ça donne. Ca a l'air de ressembler à une méthode que j'ai découvert un peu en tatonant mais le problème que j'avais c'est que je n'arrivais pas à avoir un maillage tetra progressif dans la zone "au large" de la géométrie. Donc maillage bien trop lourd et temps de calculs trop importants. Je vais lire ça en détail demain!

@Mingersai : Thank you for your input ! I already read your messages but I'll try again and see how that goes. Diamondx's method seems quite similar when it comes to the final result though, doesn't it?
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Old   February 28, 2012, 19:42
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Quote:
Originally Posted by Winglet_CFD View Post
@Diamondx : Merci pour ta réponse, j'ai téléchargé le fichier, tu peux le supprimer. Je lirai le tuto demain et je verrai ce que ça donne. Ca a l'air de ressembler à une méthode que j'ai découvert un peu en tatonant mais le problème que j'avais c'est que je n'arrivais pas à avoir un maillage tetra progressif dans la zone "au large" de la géométrie. Donc maillage bien trop lourd et temps de calculs trop importants. Je vais lire ça en détail demain!

@Mingersai : Thank you for your input ! I already read your messages but I'll try again and see how that goes. Diamondx's method seems quite similar when it comes to the final result though, doesn't it?
It looks similar... I don't really know the differences in applying to FLUENT calculations. You can find tons of threads as well as tutorials on prism layer generation. Good luck~
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Old   March 19, 2012, 01:38
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Deat Simon,

I am still not clear about how to combine the o-grid from 2Dto3D operation and the prism part near the fuselage, could you leave us a detailed introduction?

Thanks,

Zhenyu
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Old   September 24, 2012, 13:51
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I am looking for this mesh to get out of the troubles faced with tetra meshing. I tried this method but without any success. I am explaining my procedure kindly correct me and guide me where required....
First general tetra settings...Global scaling factor to 1, surface mesh method to "Patch Dependent", sizes in "Part Mesh setup" and "surface mesh setup" ofcourse when required,voulme mesh method set to "Delaunay"
Then I go to Blocking, "2D Surface Blocking", 2d to 3d with "Multizone", Ogrid around wing and fill type "Advance"....real trouble starts here....should I switch back to Mesh(terta framework) and generate volume mesh using "Generate Mesh" tab or should I stay in "Blocking" and generate mesh using "Premsh"? I tried with "Premesh" after few commands ran across console window no mesh appears not even surface mesh...where I am making mistake?
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Old   September 24, 2012, 21:36
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@CFDSeeker

Once in MultiZone, you don't go back to compute mesh. It doesn't use Octree tetra at all... You can generate a premesh and convert that to uns mesh.

Best regards,

Simon
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Old   September 24, 2012, 21:59
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So Delunay will automatically get generated while in Premesh?
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Old   September 24, 2012, 22:02
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Quote:
So Delunay will automatically get generated while in Premesh?
no i don't think so, after you use convert to unstructed mesh, you have to generate a delaunay mesh specifying your existing mesh that you just converted, if i'm not wrong...
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Old   September 25, 2012, 00:29
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@Simon @Diamondx
2D Surface blocking should be done for the whole geometry or just for the wing surfaces(I don't have fuselage in my geometry) and by which "Type" fully quad, quad dominant?
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Old   September 25, 2012, 02:01
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Quote:
Originally Posted by mingersai View Post
Hi, everyone.

I saw some mesh posted by Simon and I think I need this kind of mesh right now. Can anyone tell me the steps to generate this kind of mesh?


Thanks in advance

It seems that he built prism layer on hexa elements.
I had tried 2d surface blocking and generated hexa surface mesh, but when I tried to generate prism layer, some of hexa mesh turned in to triangles.
I tried use Octree to fill the volume first and then generate prism layer, all the hexa elements became tris.
I don't know how Simon build this mesh, it looks pretty good
Hi Guys
you must use inflation method in ICEM for generating boundary layer mesh near wall.
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Old   September 25, 2012, 08:28
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Quote:
So Delunay will automatically get generated while in Premesh?
Yes, MultiZone can generate mesh for different types of blocks; mapped, swept or free. Free blocks can be tetra (delaunay or TGrid), or hexa core.

You can preview all the mesh via "PreMesh", and then convert to unstructured to get somehting you can export to a solver.
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Old   September 25, 2012, 09:03
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2D Surface blocking should be done for the whole geometry or just for the wing surfaces(I don't have fuselage in my geometry) and by which "Type" fully quad, quad dominant?and by which method?
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Old   September 25, 2012, 10:06
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Quote:
2D Surface blocking should be done for the whole geometry or just for the wing surfaces(I don't have fuselage in my geometry) and by which "Type" fully quad, quad dominant?
If you want to use MultiZone for the fill, you need it to block everything so you have closed volumes to fill... (2D to 3D fill required a closed surface blocking)

But others may choose to generate mapped mesh on the wings, then run octree while keeping that mapped surface mesh, then run prism and then delaunay to replace the octree tetras...
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Old   October 3, 2012, 02:52
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I am trying to do this but without any success.
1. First I did surface blocking and I get what i shown in image 1, image 2 shows surface blocking on symmetry plane and image 3 shows mesh in wing tip region. Settings are also shown in the image 1.
2. Then 2d to 3d and using the settings shown in image 4, the shape of O-grid block is awful I tried to edit it using edit edge but the effort was futile
3. Image 5 & 6 shows what I get after "Premesh"
Now I don't know where I am getting it wrong, may be I have to do some blocking adjustment I also tried it but ended empty handed or may be I am making some mistake?

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Old   October 3, 2012, 03:05
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image 6 is shown here
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Old   October 3, 2012, 13:11
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R13 was the first release of MultiZone... It is much better with more recent versions.

But I would still probably mesh this simple geometry with traditional Hexa (CGrid). If you want, you could convert that block between the tip and the farfield to a swept block.
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Old   October 3, 2012, 13:19
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Quote:
But I would still probably mesh this simple geometry with traditional Hexa (CGrid). .
Meshing it with Hexa C-grid is not a problem for me but I want hybrid mesh for a particular problem and I really don't want to use prisms because for their low qulaity

Quote:
If you want, you could convert that block between the tip and the farfield to a swept block
Convert to swept block after C-grid or after multizone? what exactly you are talking about? and what does swept block do?
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