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

[GAMBIT] Boundary layer meshing problems

Register Blogs Members List Search Today's Posts Mark Forums Read

Reply
 
LinkBack Thread Tools Display Modes
Old   January 29, 2011, 11:03
Default Boundary layer meshing problems
  #1
New Member
 
Emily
Join Date: Jan 2011
Posts: 13
Rep Power: 6
gambiss is on a distinguished road
Hi

I am having trouble making a boundary layer around an aerofoil as I want a y+ as 1 so structure mesh at first (1% of the chord) then unstructure out from that (modelling a VAWT turbine with three blades).

Does anyone have any suggestion how to do this, as when I try it boundary layer function does go around the blade, and just make lines across it.

Thanks
gambiss is offline   Reply With Quote

Old   January 31, 2011, 02:31
Default
  #2
Super Moderator
 
-mAx-'s Avatar
 
Maxime Perelli
Join Date: Mar 2009
Location: Switzerland
Posts: 2,964
Rep Power: 30
-mAx- will become famous soon enough
first mesh edges from your airfoil
__________________
In memory of my friend Hervé: CFD engineer & freerider
-mAx- is offline   Reply With Quote

Old   January 31, 2011, 13:49
Default
  #3
New Member
 
Emily
Join Date: Jan 2011
Posts: 13
Rep Power: 6
gambiss is on a distinguished road
Cheers. Now when I try to mesh, I either get error: boundary layer is to high, then when I reduce it says: that mesh is not possible without interference.

I have taken off the auto smooth default. Is their anything else I should do?

Thanks
gambiss is offline   Reply With Quote

Old   February 1, 2011, 01:52
Default
  #4
Super Moderator
 
-mAx-'s Avatar
 
Maxime Perelli
Join Date: Mar 2009
Location: Switzerland
Posts: 2,964
Rep Power: 30
-mAx- will become famous soon enough
can you post a picture with the BL you try to attach
__________________
In memory of my friend Hervé: CFD engineer & freerider
-mAx- is offline   Reply With Quote

Old   February 6, 2011, 15:12
Default
  #5
New Member
 
Emily
Join Date: Jan 2011
Posts: 13
Rep Power: 6
gambiss is on a distinguished road
Still having problems, is this a fault of my meshed edge or? An gambit error, as some times it seems to work with out hassle... and see that other people are having simular problem...

https://picasaweb.google.com/1157392...56072322986802
https://picasaweb.google.com/1157392...56075170157810
https://picasaweb.google.com/1157392...56075170157810

Thanks for you help in advance!
gambiss is offline   Reply With Quote

Old   February 7, 2011, 02:19
Default
  #6
Super Moderator
 
-mAx-'s Avatar
 
Maxime Perelli
Join Date: Mar 2009
Location: Switzerland
Posts: 2,964
Rep Power: 30
-mAx- will become famous soon enough
if you deselect the trailing edge in the BL-surface list, does the error remain?
__________________
In memory of my friend Hervé: CFD engineer & freerider
-mAx- is offline   Reply With Quote

Old   February 7, 2011, 07:01
Default
  #7
New Member
 
Emily
Join Date: Jan 2011
Posts: 13
Rep Power: 6
gambiss is on a distinguished road
If you mean, not creating a boundary layer around the trailing edge then no, this doesn't work either!

But unsure of what you mean!
gambiss is offline   Reply With Quote

Old   February 7, 2011, 07:54
Default
  #8
Super Moderator
 
-mAx-'s Avatar
 
Maxime Perelli
Join Date: Mar 2009
Location: Switzerland
Posts: 2,964
Rep Power: 30
-mAx- will become famous soon enough
no I mean, don't pick the trailing edge, when you select edges where the BL will be attached.
Does the error remain?
Quote:
Originally Posted by gambiss View Post
Now when I try to mesh, I either get error: boundary layer is to high, then when I reduce it says: that mesh is not possible without interference. Thanks
__________________
In memory of my friend Hervé: CFD engineer & freerider
-mAx- is offline   Reply With Quote

Old   February 7, 2011, 08:08
Default
  #9
New Member
 
Emily
Join Date: Jan 2011
Posts: 13
Rep Power: 6
gambiss is on a distinguished road
Yes, now it will mesh, is there any way to get it create a boundary layer around the whole blade?

Thanks!
gambiss is offline   Reply With Quote

Old   February 8, 2011, 01:58
Default
  #10
Super Moderator
 
-mAx-'s Avatar
 
Maxime Perelli
Join Date: Mar 2009
Location: Switzerland
Posts: 2,964
Rep Power: 30
-mAx- will become famous soon enough
ok that means the error comes from this edge.
Try to add more nodes on this edge.
If it don't help, try to merge the edge with the 2 others (both sides), and perturb nodes distribution
__________________
In memory of my friend Hervé: CFD engineer & freerider
-mAx- is offline   Reply With Quote

Old   February 8, 2011, 05:42
Default
  #11
New Member
 
Emily
Join Date: Jan 2011
Posts: 13
Rep Power: 6
gambiss is on a distinguished road
I've managed to Mesh it now, but, it is really skewed next to the blade, is this just from the position of the nodes and is the only way to solve this adjusting them?

Or is there a simpler way!?

Thanks for all you help, I really appreciate it!
gambiss is offline   Reply With Quote

Old   February 8, 2011, 05:51
Default
  #12
Super Moderator
 
-mAx-'s Avatar
 
Maxime Perelli
Join Date: Mar 2009
Location: Switzerland
Posts: 2,964
Rep Power: 30
-mAx- will become famous soon enough
post a picture
__________________
In memory of my friend Hervé: CFD engineer & freerider
-mAx- is offline   Reply With Quote

Old   February 8, 2011, 06:01
Default
  #13
New Member
 
Emily
Join Date: Jan 2011
Posts: 13
Rep Power: 6
gambiss is on a distinguished road
https://picasaweb.google.com/1157392...56384960415330

https://picasaweb.google.com/1157392...56392982700834
gambiss is offline   Reply With Quote

Old   February 8, 2011, 06:04
Default
  #14
Super Moderator
 
-mAx-'s Avatar
 
Maxime Perelli
Join Date: Mar 2009
Location: Switzerland
Posts: 2,964
Rep Power: 30
-mAx- will become famous soon enough
something is weird.
Can you provide me the dbs file?
__________________
In memory of my friend Hervé: CFD engineer & freerider
-mAx- is offline   Reply With Quote

Old   February 8, 2011, 06:59
Default
  #15
New Member
 
Emily
Join Date: Jan 2011
Posts: 13
Rep Power: 6
gambiss is on a distinguished road
http://www.fileswap.com/dl/eQjBziUI/...again.zip.html
gambiss is offline   Reply With Quote

Old   February 8, 2011, 08:30
Default
  #16
Super Moderator
 
-mAx-'s Avatar
 
Maxime Perelli
Join Date: Mar 2009
Location: Switzerland
Posts: 2,964
Rep Power: 30
-mAx- will become famous soon enough
ok I kept the parameters from your BL and your SF.
But first, you absolutely need to split your domain into several smallest surfaces.
Indeed you have 3 airfoils, so I would isolate each airfoil with a split (circle in my example)
Then Gambit will have less difficulty to mesh surfaces, especially when you impose a thin BL.
So I meshed one airfoil with this method (you choosed tri), but here you can easily mesh it with hexa.
I would mesh it with hexa ,then you can have more control on the aspect ratio between last cell layer from your BL and cells outside the BL.
Sans titre.jpgSans titre2.pngSans titre3.jpg
__________________
In memory of my friend Hervé: CFD engineer & freerider
-mAx- is offline   Reply With Quote

Old   February 8, 2011, 10:18
Default
  #17
New Member
 
Emily
Join Date: Jan 2011
Posts: 13
Rep Power: 6
gambiss is on a distinguished road
Okay, thanks for that! I will reduce my surfaces...

But- I can only select hexa in volume meshing? How do I do it for 2D? :?
gambiss is offline   Reply With Quote

Old   February 8, 2011, 10:52
Default
  #18
Super Moderator
 
-mAx-'s Avatar
 
Maxime Perelli
Join Date: Mar 2009
Location: Switzerland
Posts: 2,964
Rep Power: 30
-mAx- will become famous soon enough
quad or map
__________________
In memory of my friend Hervé: CFD engineer & freerider
-mAx- is offline   Reply With Quote

Old   February 9, 2011, 07:31
Default
  #19
New Member
 
Emily
Join Date: Jan 2011
Posts: 13
Rep Power: 6
gambiss is on a distinguished road
Hmm, I've meshing the blades seperately but I still get the same skewed BL around them...
gambiss is offline   Reply With Quote

Old   February 9, 2011, 07:58
Default
  #20
Super Moderator
 
-mAx-'s Avatar
 
Maxime Perelli
Join Date: Mar 2009
Location: Switzerland
Posts: 2,964
Rep Power: 30
-mAx- will become famous soon enough
with quad or tri?
As you saw, with tri I didn't have any problem
post pictures
__________________
In memory of my friend Hervé: CFD engineer & freerider
-mAx- is offline   Reply With Quote

Reply

Thread Tools
Display Modes

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 On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
SnappyHexMesh - no layer added bejbro OpenFOAM Mesh Utilities 4 October 16, 2014 19:24
boundary layer meshing chenwen521 FLUENT 1 September 4, 2009 10:29
*** Guidelines on Boundary Layer Meshing *** Carlos FLUENT 3 March 19, 2008 09:29
Boundary layer meshing with sharp trailing edges Andrew Berner FLUENT 1 August 28, 2007 17:39
Boundary layer simulation - convergence problems Gavin Tabor Main CFD Forum 3 July 2, 2004 05:16


All times are GMT -4. The time now is 07:42.