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

Role of Phi in pimpleDyMFoam

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

Like Tree1Likes
  • 1 Post By deepsterblue

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   April 2, 2012, 06:10
Default Role of Phi in pimpleDyMFoam
  #1
Member
 
fisch
Join Date: Feb 2010
Posts: 97
Rep Power: 16
fisch is on a distinguished road
Hello,

i am working with the pimpleDyMFoam solver.
In pEqn.H the U and therefore the phi are derived out of

U = rAU*UEqn().H();
phi = (fvc::interpolate(U) & mesh.Sf());

As i get it the fluxes in the UEqn are relative (which should be correct).
Isn't therefore the flux term inside the mentioned phi relative, too?

If yes, i don't understand why phi will be made relative (again) after solving the pEqn!?


thanks in advance,
rupert
fisch is offline   Reply With Quote

Old   April 2, 2012, 11:41
Default
  #2
Senior Member
 
Sandeep Menon
Join Date: Mar 2009
Location: Amherst, MA
Posts: 403
Rep Power: 25
deepsterblue will become famous soon enough
Not really...

phi = (fvc::interpolate(U) & mesh.Sf());

In this case, phi is not relative to mesh-fluxes. It's just the absolute volumetric flux. Mesh-fluxes are factored-in only during the momentum solve (where a makeRelative has been called). Inside the PISO / SIMPLE / PIMPLE loop, fluxes are always assumed to be absolute.

It's made relative (again) after the pEqn solve because the U.correctBoundaryConditions() call might require relative fluxes for certain types of momentum BCs, like a movingWallVelocity, for instance.
__________________
Sandeep Menon
University of Massachusetts Amherst
https://github.com/smenon
deepsterblue is offline   Reply With Quote

Old   April 2, 2012, 12:50
Default
  #3
Member
 
fisch
Join Date: Feb 2010
Posts: 97
Rep Power: 16
fisch is on a distinguished road
Thanks for the answer.

The only one question is why the phi is made absolute at the begin of a time loop!?!
fisch is offline   Reply With Quote

Old   April 2, 2012, 12:52
Default
  #4
Senior Member
 
Sandeep Menon
Join Date: Mar 2009
Location: Amherst, MA
Posts: 403
Rep Power: 25
deepsterblue will become famous soon enough
That's simple. When fluxes are written to disk at runTime.write(), they're relative. Since meshPhi is also written to disk, all the necessary info is available when a restart is done.
lth likes this.
__________________
Sandeep Menon
University of Massachusetts Amherst
https://github.com/smenon
deepsterblue is offline   Reply With Quote

Old   April 2, 2012, 15:14
Default
  #5
Member
 
fisch
Join Date: Feb 2010
Posts: 97
Rep Power: 16
fisch is on a distinguished road
thank you very much
fisch 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


Similar Threads
Thread Thread Starter Forum Replies Last Post
phi -= pEqn.flux() vs. linearInterpolate(U) & mesh.Sf() santiagomarquezd OpenFOAM Programming & Development 33 October 15, 2019 11:24
Turbulence Model phi vs phi_ doug OpenFOAM Running, Solving & CFD 4 November 10, 2009 05:33
Another phi question ehsan_vaghefi OpenFOAM Running, Solving & CFD 0 October 24, 2008 20:56
About phi in icoFoam kar OpenFOAM Running, Solving & CFD 3 February 20, 2008 06:20


All times are GMT -4. The time now is 15:44.