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

Source term in NS eqns

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

Reply
 
LinkBack Thread Tools Display Modes
Old   January 30, 2006, 20:48
Default Source term in NS eqns
  #1
zonexo
Guest
 
Posts: n/a
hi,

may I know if there is a need to add a source term which contains rotational/coriolis effect?

I'm trying to solve the NS eqns in ALE formulation with moving/deforming meshes due to plunging & pitching airfoil motion.

thanks!
  Reply With Quote

Old   January 30, 2006, 22:59
Default Re: Source term in NS eqns
  #2
ag
Guest
 
Posts: n/a
If the coordinate system you are solving the equations in is rotating then yes you need to add a term to account for the motion of the coordinate system.
  Reply With Quote

Old   January 31, 2006, 00:33
Default Re: Source term in NS eqns
  #3
zonexo
Guest
 
Posts: n/a
thanks ag...

in other words, if i 've a pitching aifoil and the grid deforms at the airfoil surface but it is fixed at the outside boundary, there is no need for the additional source term, right?

similarly, if the airfoil is accelerating up together with the grid, there is also no source term required, cause there's no angular velocity/acceleration, right?

thanks again...
  Reply With Quote

Old   January 31, 2006, 01:08
Default Re: Source term in NS eqns
  #4
ganesh
Guest
 
Posts: n/a
Dear Zonexo,

There is no need to add any source term corressponding to the coriolis effect, as long as your frame of reference is inertial. Coriolis componenet comes in when there is a non-inertial frame( such as rotating) of reference.

To reduce the complexity, you could first try it out for a few Euler cases and then can easily incorporate into N/S

Regards

Ganesh

  Reply With Quote

Old   January 31, 2006, 09:50
Default Re: Source term in NS eqns
  #5
ag
Guest
 
Posts: n/a
See ganesh's response. Grid motion has nothing to do with the existence of a Coriolis source term. The Coriolis acceleration arises if the basis vectors you are using to describe your vector and tensor quantities are rotating. An additional source term would appear if they are linearly accelerating. The easiest way to see if this is the case is to consider a uniform freestream in the coordinate system you are using. Are the velocity components of the uniform freestream changing in time? If so then your coordinate system is accelerating and you will need to capture that in the formulation of the governing equations. But to emphasize - grid motion has nothing to do with the need for a Coriolis source term.
  Reply With Quote

Old   February 3, 2006, 18:33
Default Re: Source term in NS eqns
  #6
Valerio D'Alessandro
Guest
 
Posts: n/a
I don't know very well your problem and i didn't read your message with necessary attection. When you suppose that Coriolis force acts in the problem is always good rule estimate Rossby Number effect!!!

Ro=u/(2omega*L)
  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
swak4foam building problem GGerber OpenFOAM Installation 54 April 24, 2015 16:02
momentum source term zwdi FLUENT 13 December 5, 2013 18:58
DxFoam reader update hjasak OpenFOAM Post-Processing 69 April 24, 2008 01:24
DecomposePar links against liblamso0 with OpenMPI jens_klostermann OpenFOAM Bugs 11 June 28, 2007 17:51
UDF Scalar Code: HT 1 Greg Perkins FLUENT 8 October 20, 2000 12:40


All times are GMT -4. The time now is 07:55.