CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > CFX

Stationary and Rotating Domains

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

Like Tree2Likes
  • 2 Post By ghorrocks

Reply
 
LinkBack Thread Tools Display Modes
Old   April 30, 2014, 09:11
Default Stationary and Rotating Domains
  #1
Member
 
Daniel Frederik
Join Date: Apr 2014
Location: Switzerland
Posts: 38
Rep Power: 3
Daniel Frederik is on a distinguished road
Hello Fluiders,

I simulated 3 Domains as shown in the picture. i know it's kinda funny cause it doesnt simulate anything useful. Anyways the problem is interesting. The two Domains of both ends are stationnary, the one in the middle rotaes. Now actually the mesh is rotating but since there is nothing in that middle section that could make the fluid rotate it is quite interesting to see that the streamlines show a rotation in the middle section. Does anyone have an idea what that is due to?
Attached Images
File Type: jpg Sans titre.jpg (48.1 KB, 33 views)
Daniel Frederik is offline   Reply With Quote

Old   April 30, 2014, 13:47
Default
  #2
Senior Member
 
Join Date: Jun 2009
Posts: 288
Rep Power: 9
Opaque is on a distinguished road
What boundary condition for velocity are you using on the outer wall ?

No Slip in the rotating frame, or in the stationary frame ?
Opaque is offline   Reply With Quote

Old   April 30, 2014, 14:41
Default
  #3
Member
 
Daniel Frederik
Join Date: Apr 2014
Location: Switzerland
Posts: 38
Rep Power: 3
Daniel Frederik is on a distinguished road
I'm using No Slip on both. Maybe it is some sort of a local coordinate system that makes it just appear that way.
Daniel Frederik is offline   Reply With Quote

Old   April 30, 2014, 18:20
Default
  #4
Senior Member
 
Join Date: Jun 2009
Posts: 288
Rep Power: 9
Opaque is on a distinguished road
That seems to be the problem.

If you are in the rotating frame, a stationary wall counter rotates; otherwise, you are imposing a rotating wall in the stationary frame.
  • No Slip stationary wall in the rotating frame = No Slip Rotating wall in the stationary frame
  • No Slip counter-rotating wall in the rotating frame = No Slip stationary wall in the stationary frame.

Either will be consistent with the walls in the upstream and downstream domains, and you should not see the rotation in the stream lines (barring discretization errors)
Opaque is offline   Reply With Quote

Old   May 1, 2014, 05:37
Default
  #5
Member
 
Daniel Frederik
Join Date: Apr 2014
Location: Switzerland
Posts: 38
Rep Power: 3
Daniel Frederik is on a distinguished road
Thank you for the suggestion. I tryed so but had no succes. I doubt that it has to do with the walls. The domains are in different referential frames, a rotating wall would just affect the boundary layer not the whole fluid.
But why would cfx post not show the movement of the fluid in the absolute coordinate system?
Daniel Frederik is offline   Reply With Quote

Old   May 1, 2014, 06:28
Default
  #6
Member
 
Daniel Frederik
Join Date: Apr 2014
Location: Switzerland
Posts: 38
Rep Power: 3
Daniel Frederik is on a distinguished road
Here the same problem without rotating walls, only a rotating domain Inside a stationary.
The pictures show the streamlines of each domain. There again in the rotating domain the streamlines are not straight. Why??
If you for instance want to simulate a Wind turbine you would put that one into the rotating domain, and the turbine would affect the fluid flow, but since there is no obstacle in this case...
Attached Images
File Type: jpg Stream 1.jpg (27.4 KB, 18 views)
File Type: jpg Stream 2.jpg (38.1 KB, 21 views)
Daniel Frederik is offline   Reply With Quote

Old   May 1, 2014, 09:14
Default
  #7
Super Moderator
 
Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 10,795
Rep Power: 84
ghorrocks has a spectacular aura aboutghorrocks has a spectacular aura aboutghorrocks has a spectacular aura about
Don't forget you need to plot velocity in stn frame, not just velocity.
ghorrocks is offline   Reply With Quote

Old   May 1, 2014, 09:29
Default
  #8
Member
 
Daniel Frederik
Join Date: Apr 2014
Location: Switzerland
Posts: 38
Rep Power: 3
Daniel Frederik is on a distinguished road
Thank you very much!
Daniel Frederik 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
Rotating and stationary walls martijnal CFX 2 June 14, 2013 03:32
Forces in global frame for rotating domains? xGlobal? cycleodyssey CFX 0 March 17, 2013 19:00
Frozen Rotor 1:1 Mesh Connection pharley CFX 5 January 31, 2013 17:15
Viewing Rotating and Stationary Domains in Post tango711 CFX 1 August 23, 2012 08:09
rotating propeller in stationary baffled vessel wlt_1985 FLUENT 27 March 30, 2011 01:22


All times are GMT -4. The time now is 01:03.