CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > OpenFOAM Meshing & Mesh Conversion

Wing - internal flow

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

Reply
 
LinkBack Thread Tools Display Modes
Old   December 3, 2011, 12:52
Default Wing - internal flow
  #1
Member
 
Join Date: Jun 2011
Posts: 37
Rep Power: 6
ChrisPro is on a distinguished road
Hello!

I'm trying to mesh a stl file of a wing.The wing is hollow and I want to simulate the internal flow, from one side of the wing to the other. So the inlet should more or less have the shape of an airfoil profile. The wing has some holes where the fluid can get through, so also the outside of the wing hast to be meshed.

At the inlet i only set the pressure. the velocity is calculated according to it.
But it is really important, that all of the flow gets throug the paraglider.
To mesh the file I use snappyHexMesh, of course.
But, now that I've tried several ways and didn't succeed, I need your help!

In the blockMeshDict file i made a block, where the stl file is in and touches one face of the block with its open side. To make a airfoil shaped inlet, I made another block, with splined edges and merged it to the first block.

But when i start snappyHexMesh I alsoways get the FATAL ERROR:
cell 15 (or any other number) of level 0 uses more than 8 points of equal or lower level


I also tried to give the face of the first block the shape of the airfoil and make this the inlet, but that doesn't work either.

Has anyone an idea, how I can fix this problem?

regards
Christian
ChrisPro is offline   Reply With Quote

Old   May 10, 2012, 10:10
Default Similar problem
  #2
New Member
 
Join Date: Feb 2012
Posts: 4
Rep Power: 5
Antti is on a distinguished road
Hi,

Did you find a solution to your problem? Because I'm having a similar crash with sHM and can't find any info on what is causing it and how to stop it from happening. The only clue is that changing maxGlobalCells in castellatedMeshControls to a lower value seems to make the error go away. Trouble is that I'd need more detail for the mesh and so a larger number of cells.

-Antti
Antti is offline   Reply With Quote

Old   May 10, 2012, 13:29
Default
  #3
Member
 
Join Date: Jun 2011
Posts: 37
Rep Power: 6
ChrisPro is on a distinguished road
Hey Antti!

Yes, If you want to mesh a stl-geometry from the inside, just make a mesh with blockMesh which covers the geometry and then set the "locationInMesh" to a point inside the geometry.

this is it

greets
Christian
ChrisPro is offline   Reply With Quote

Old   May 11, 2012, 04:49
Default
  #4
New Member
 
Join Date: Feb 2012
Posts: 4
Rep Power: 5
Antti is on a distinguished road
Hi Christian,

Thanks for your reply. My case is different in that I actually want to mesh the outside of an object, but similar in that it produces this error you were having:

Quote:
But when i start snappyHexMesh I alsoways get the FATAL ERROR:
cell 15 (or any other number) of level 0 uses more than 8 points of equal or lower level
I guess selecting the correct locationInMesh fixed it in your case? Maybe the reason is different for me. I can get it to build the mesh when global number of cells is set to 2M, I think this prevents sHM from doing the suface refinement which is apparently the part of sHM having this problem.

Thanks again for your reply.

greets,

Antti
Antti is offline   Reply With Quote

Old   May 11, 2012, 14:35
Default
  #5
Member
 
Join Date: Jun 2011
Posts: 37
Rep Power: 6
ChrisPro is on a distinguished road
...and you're sure you didn't set the locationInMesh variable to a value which is directly on the surface?
Try to set this variable to a completely different value. for instance a meter away from the geometry
ChrisPro is offline   Reply With Quote

Old   May 18, 2012, 02:54
Smile
  #6
New Member
 
Join Date: Feb 2012
Posts: 4
Rep Power: 5
Antti is on a distinguished road
That was probably the reason, thanks! I'd set the locationInMesh too close to the surface.

But I'm still saying "probably" because snappyHexMesh still crashes, only now because it doesn't honor the maxGlobalCells limit and runs out of memory in the Shell Refinement phase. I'm going to try to find a solution for that now.
Antti is offline   Reply With Quote

Old   May 18, 2012, 03:26
Default
  #7
Member
 
Join Date: Jun 2011
Posts: 37
Rep Power: 6
ChrisPro is on a distinguished road
k

maybe you have a symmetry plane in your case, then you can simulate just half of the case. This would need much less memory!

If not you propably have to use a computer with more memory

greets
Christian
ChrisPro 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
flow modeling and incompressible analysis of internal flow of effervescent injector umar959 FLUENT 0 November 15, 2011 04:32
Pipe flow / Internal fluid dynamics with SnappyHexMesh denner OpenFOAM Native Meshers: snappyHexMesh and Others 3 October 13, 2011 09:24
Modelling flow around a flapping wing balkrishna Main CFD Forum 1 February 19, 2010 00:32
Setting up Flow around a Wing Simulation help Atella CFX 3 January 3, 2010 12:51
Why Re is different for external and internal flow john FLUENT 3 June 14, 2007 03:53


All times are GMT -4. The time now is 01:04.