CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > Software User Forums > ANSYS > ANSYS Meshing & Geometry

[ICEM] Meshing Problem ?

Register Blogs Community New Posts Updated Threads Search

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   November 13, 2014, 06:38
Default Meshing Problem ?
  #1
New Member
 
Join Date: Jul 2013
Posts: 21
Rep Power: 13
Leifheit is on a distinguished road
Hello everyone,

I came across quite a weird problem.
I am simulating 2D flow around an airfoil with CFX. I am using the SST Gamma Theta Transition Model. The mesh is generated with ICEM.

My simulations reach convergence (1st attached picture) and everything seemed to be fine (velocity / pressure field / ... ) - then I took a look at the wall shear behaviour (2nd attached picture) - its is really jumpy which isnt right.

Now this might not sound like a meshing problem but I ve tried changing a lot of different parameters in CFX all with no success. Then I used a mesh a colleague of mine created with the exact same settings for CFX (considering turbulence model / settings / ... ) resulting in good results - thats why I am pretty sure this is a meshing problem.

I already did a mesh study on this (Yplus, streamwise grid refinement, cell expansion rate) but nothing solved the problem so I think there might be something wrong with the way I created my mesh.
Ive also attached the .rpl file of my mesh. (3rd attachment)

Hope anyone has ideas on this since Its really bugging me and I want to know whats wrong

If you need any additional information be sure to tell me !

Best Regards,

Leif
Attached Images
File Type: jpg residuals.jpg (45.1 KB, 23 views)
File Type: jpg wallshear1.jpg (37.9 KB, 22 views)
Attached Files
File Type: c NACArpl.c (28.8 KB, 7 views)
Leifheit is offline   Reply With Quote

Old   November 14, 2014, 18:06
Default
  #2
Member
 
davide basso
Join Date: Jan 2012
Posts: 48
Rep Power: 14
rolloblues is on a distinguished road
Hi,
running the script ICEM complains about a missing Nacapoints file

Can you attach it as well?
rolloblues is offline   Reply With Quote

Old   November 19, 2014, 09:36
Default
  #3
New Member
 
Join Date: Jul 2013
Posts: 21
Rep Power: 13
Leifheit is on a distinguished road
hi !

sorry about the late answer ... here is the NACA file ... you have to remove the .txt file ending though
Attached Files
File Type: txt Nacapoints.txt (992 Bytes, 2 views)
Leifheit is offline   Reply With Quote

Old   December 4, 2014, 19:09
Default
  #4
Member
 
davide basso
Join Date: Jan 2012
Posts: 48
Rep Power: 14
rolloblues is on a distinguished road
Hi there,
first of all sorry for the horrible delay of this reply.

Loading the replay script I noticed at least two things:
- quality is below 0.3 for about 100 elements and this could be e a problem, especially because they are located at the nose and the trailing edge of the airfoil.
- the nacapoints define a profile with a sharp trailing edge (the pressure side and the suction side converge to a point) but in your geometry the trailing edge is truncated...why?


In your case I would rather go for a 2D C-shaped blocking approach as, for instance, in the pictures attached.
Once the premesh is good enough, you can generate the 2D mesh and then extrude it to obtain the 3D mesh ready to be exported straight away, without the hassle of extruding the geometry also.

Hope this helps
Attached Images
File Type: jpg blocks.jpg (23.8 KB, 9 views)
File Type: jpg 2Dmesh1.jpg (73.7 KB, 10 views)
File Type: jpg 2Dmesh2.jpg (47.7 KB, 8 views)
rolloblues is offline   Reply With Quote

Reply


Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Problem with querying the meshing database in CFX-Pre ashtonJ CFX 18 April 19, 2023 00:49
[Other] Hex meshing problem DM12 patrick ANSYS Meshing & Geometry 7 January 9, 2015 08:21
[ANSYS Meshing] Inflation - Airfoil Meshing - Divergence problem dalecooper ANSYS Meshing & Geometry 0 July 19, 2013 08:04
Meshing problem in GAMBIT Vidya Raja FLUENT 0 May 21, 2006 00:31
GAMBIT meshing problem Gauthier Lambert Main CFD Forum 1 August 3, 2000 10:22


All times are GMT -4. The time now is 10:12.