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July 14, 2013, 22:49 |
unknown pre-mesh distortion
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#1 |
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Dear veteran meshers,
After long and repeated meshing work ,i got quite a frustrated results:the mesh over one side of the aircraft is mysteriously distorted ,while the opposite side is fine.The two sides are symmetrical. I did the association work for curves and faces all over again,but the results are the same.Can you help locate the problem of this issue,I really don't want to redo the blocking and splitting.... |
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July 15, 2013, 02:30 |
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#2 |
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problem solved after re-create the nacelle geometry.
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July 15, 2013, 07:52 |
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#4 |
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yes,FAR.quite stupid I know ,very grid-inefficient,already got 600 million,barely run on my 16G RAM PC.
Just want to see the whole picture. Still got the Y-block generated mesh around the dorsal fin with ANGLE critiria like shit ,any suggestions? |
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July 15, 2013, 12:13 |
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#6 |
Super Moderator
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It will take some time. Look at the meshes by Simon done for drag prediction workshop
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July 15, 2013, 15:55 |
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#7 | |
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Quote:
Regards. |
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July 16, 2013, 22:56 |
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#8 | |
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Quote:
Thanks for reply,how do you think i should simplify the geometry,for me it's already the basic aerodynamic shape of a aircraft. And the engine exhaust blocks are already splitted like this: |
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July 16, 2013, 23:12 |
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#9 |
Member
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I suggest you to use a symmetry boundary condition in order to reduce the number of cells and to simplify the blocking procedure. Otherwise you will require a huge quantity of memory to be able to load the mesh into fluent or any other CFD code. I also see that you have a Y-block right behind the exhaust of the nozzle, which in my particular point of view is adding unnecessary complexity to the blocking topology.
I guess that diamondx is suggesting to implement an o-grid topology at the face of the exhaust like the one shown in the attached picture. That would help to avoid significantly those distorted cells you have in your recent mesh. http://laurent.nack.pagesperso-orang...cem/grido1.gif Regards, César |
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July 16, 2013, 23:25 |
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#10 |
Super Moderator
Ghazlani M. Ali
Join Date: May 2011
Location: Tokyo, Japan
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Another thing, you could have used symmetry for your geometry and then transforming that mesh by mirroring it...
@FAR, have you got any geometry like this, this can be a good subject for a contest... |
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July 17, 2013, 21:48 |
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#11 |
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July 17, 2013, 21:57 |
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#12 | |
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Quote:
those cells are distorted due to some geometry association promblem,already smoothed after re-create part. Didn't use the split-in-half model because i really want to see the unsymmetrical flow pattern expected for later purposes. And for Y-block,i just don't know any other methods to split a sharp edge wing tip block. |
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July 17, 2013, 22:02 |
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#13 |
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July 17, 2013, 22:30 |
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#14 | |
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Quote:
Thank you Cesar,very good suggestion,much appreciated. That o-grid should eliminate the low quality cells at the end of cylinder-shaped nacelles and fuselage,I suppose? Also I didn't use symmetry boundary because i had unrealistic confidence of my 8-core 16G ram PC(I used to have a Pentium 4 with 2G ram that can handle 1 million grids),infact 600 million is alomost the limit for now,with first-order and turbulence on.I'll resort to half model if this full hexa approach dosen't work out. Please shine some light on the blocking strategy for my four sharp edge parts without using Y-block:wings,horizental tail,nacelles,dorsal fin(pointed at the frontmost) . |
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July 19, 2013, 01:28 |
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#15 | |||
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Regards. |
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