CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > Software User Forums > OpenFOAM > OpenFOAM Running, Solving & CFD

Strange mesh dependent result of a pipe flow with SSG

Register Blogs Community New Posts Updated Threads Search

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   November 8, 2017, 06:24
Default Strange mesh dependent result of a pipe flow with SSG
  #1
New Member
 
Andi
Join Date: Feb 2014
Location: Berlin
Posts: 6
Rep Power: 12
swin-joe is on a distinguished road
Hello everybody,

I have simulated a simple turbulent pipe flow with the SSG turbulence model. The residuals converge. Some probs are constant.
I only use linear or limitedLinear schemes in the Divergence scheme. With the Surface-normal gradient I use the Corrected schemes. However, the result shows a strong dependence on the mesh or the orientation of the mesh.
A refinement delivers the same result.
I used wall functions at yPlus = 30.
Is there any hint, what I can try.

Best regards
And I
Attached Images
File Type: png Vel_Mag.png (130.5 KB, 40 views)
swin-joe is offline   Reply With Quote

Old   November 9, 2017, 05:14
Default
  #2
New Member
 
Andi
Join Date: Feb 2014
Location: Berlin
Posts: 6
Rep Power: 12
swin-joe is on a distinguished road
Hello

has anyone some experience with the SSG Reynolds Stress Model?

Best Regards
Andi
swin-joe is offline   Reply With Quote

Old   November 9, 2017, 17:03
Default
  #3
New Member
 
JPeternel
Join Date: Oct 2014
Posts: 19
Rep Power: 12
jpeter3 is on a distinguished road
Generally, every solution is mesh dependent ... maybe introducing nonOrthogonal correctors or bigger number of PISO correctors can give you better results.

Also, results usually converge when increasing mesh density. Also, using smooth transitions from one type of meshing to another improve results, those triangles may be causing the trouble ...
jpeter3 is offline   Reply With Quote

Old   November 10, 2017, 01:14
Default
  #4
Senior Member
 
piu58's Avatar
 
Uwe Pilz
Join Date: Feb 2017
Location: Leipzig, Germany
Posts: 744
Rep Power: 15
piu58 is on a distinguished road
The construction of the mesh may be better:
1) The transition form the radial elements to the rectangular is far to close to the edge.
2) I would look for a construction idea where the transition is nut such abrupt
3) I would use only square/hexagonal elements an avoid abnormal triangular ones
__________________
Uwe Pilz
--
Die der Hauptbewegung überlagerte Schwankungsbewegung ist in ihren Einzelheiten so hoffnungslos kompliziert, daß ihre theoretische Berechnung aussichtslos erscheint. (Hermann Schlichting, 1950)
piu58 is offline   Reply With Quote

Reply

Tags
pipe flow, ssg, turbulence models


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
Gambit problems Althea FLUENT 22 January 4, 2017 04:19
mesh 3d pipe with turbulent flow amin4547 FLUENT 0 June 7, 2015 15:27
sonicFoam - pressure driven pipe: flow continuity violation and waveTransmissive BC Endel OpenFOAM Running, Solving & CFD 3 September 11, 2014 17:29
strange result for non-orthogonality mesh using icoFoam xiaof OpenFOAM 1 November 2, 2013 08:48
flow in perforated pipe distributor pertupd ANSYS 0 August 12, 2009 09:36


All times are GMT -4. The time now is 23:32.