CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > Software User Forums > Siemens > STAR-CCM+

Moment around and axis or on a plane

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

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   June 24, 2010, 16:48
Default Moment around and axis or on a plane
  #1
New Member
 
Join Date: May 2010
Posts: 9
Rep Power: 15
Dora is on a distinguished road
Hello everyone,
I'm trying to have the air tumble in a pipe calculated.
I placed a cylindrical coordinate system in the centre of the pipe and need the moment/torque around the Z axis. Through the X-Y planes of the coordinate system I also placed a plane (not shown on the pic). Then I tried to have the generate torque calculated on the plane which was unsuccessful. I then tried another approach. I have created a report --> moment with the parts chosen "out". Here the coordinate system laboratory is chosen which I cant change to cylindrical coordinate system which would probably give me the torque.

Can anyone help me to get use of on of the approaches I have taken please.

Thank you very much.
regards, CS



Dora is offline   Reply With Quote

Old   June 24, 2010, 17:35
Default
  #2
Member
 
Vinicius Girardi
Join Date: Mar 2009
Location: Sao Paulo, Brazil
Posts: 80
Rep Power: 17
Vinicius is on a distinguished road
Just copy the Z direction of your cylindrical coordinate system in the "Axis" field and set the origin in a Moment Report... Go to the Tools->Coordinate system and select your Coord. to get this information...
Vinicius is offline   Reply With Quote

Old   June 25, 2010, 16:24
Default
  #3
New Member
 
Join Date: May 2010
Posts: 9
Rep Power: 15
Dora is on a distinguished road
Thank you for your reply. I have tried that and I get an result. Is there any way to cross check the result? The thing is I only get a torque if I chose an axis which is not on the centreline of the pipe. Currently Im having Z lying on the centreline. When I set in the report --> moment --> 0.0, 0.0, 1.0, it shows me 0.000Nm. When I switch to 1.0, 0.0, 0.0 I get some torque.

Thanks again
Dora is offline   Reply With Quote

Old   June 25, 2010, 17:43
Default
  #4
f-w
Senior Member
 
Join Date: Apr 2009
Posts: 153
Rep Power: 16
f-w is on a distinguished road
Does your pipe geometry suggest you should be expecting any tumbling? It might help to plot in-plane (XY) velocities to see what's going on ...
f-w is offline   Reply With Quote

Old   June 25, 2010, 17:51
Default
  #5
New Member
 
Join Date: May 2010
Posts: 9
Rep Power: 15
Dora is on a distinguished road
Yes it does. See the pic http://www.casa-tec.com/Bild1.jpg.
I applied streamlines to see what is happening. As said earlier, around x and y it gives me a moment, not around Z which it should.
I have been struggling with this for quite some time. I could upload the file on a server if anyone would be free to check the setting.

regards, CS
Dora is offline   Reply With Quote

Old   June 25, 2010, 19:42
Default
  #6
f-w
Senior Member
 
Join Date: Apr 2009
Posts: 153
Rep Power: 16
f-w is on a distinguished road
Are you running an inviscid simulation?
f-w is offline   Reply With Quote

Old   June 26, 2010, 08:46
Default
  #7
New Member
 
Join Date: May 2010
Posts: 9
Rep Power: 15
Dora is on a distinguished road
Hi sure what is meant by that.
I'm running the "turbulent visocisty ratio" at 10, "turbulence intensity" at 0.05 a "No-Slip" wall conditions. I have the measured mass flow data and the CFD prediction is closer to the testing results when "No-Slip" is set. Pressure applied at the outlet is -2500Pa.
Dora is offline   Reply With Quote

Old   June 26, 2010, 09:41
Default
  #8
Member
 
Vinicius Girardi
Join Date: Mar 2009
Location: Sao Paulo, Brazil
Posts: 80
Rep Power: 17
Vinicius is on a distinguished road
Upload the file and I can take a look...
Vinicius is offline   Reply With Quote

Old   June 26, 2010, 09:51
Default
  #9
New Member
 
Join Date: May 2010
Posts: 9
Rep Power: 15
Dora is on a distinguished road
Thats great. Please send me your email on c.sansanelli@hotmail.com and Ill give you the link.

Thanks again.
Dora is offline   Reply With Quote

Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
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 Off
Pingbacks are On
Refbacks are On



All times are GMT -4. The time now is 02:13.