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

About phi in icoFoam

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

Like Tree4Likes
  • 4 Post By schmidt_d

Reply
 
LinkBack Thread Tools Display Modes
Old   February 18, 2008, 16:59
Default Hi! U = rUA*UEqn.H(); phi
  #1
kar
Senior Member
 
Kārlis Repsons
Join Date: Mar 2009
Location: Latvia
Posts: 111
Rep Power: 8
kar is on a distinguished road
Hi!

U = rUA*UEqn.H();
phi = (fvc::interpolate(U) & mesh.Sf())
+ fvc::ddtPhiCorr(rUA, U, phi);

What fvc::ddtPhiCorr(rUA, U, phi) is there for?

if (nonOrth == nNonOrthCorr)
{
phi -= pEqn.flux();
}

And what ".flux()" is returning?

Kārlis
kar is offline   Reply With Quote

Old   February 19, 2008, 13:47
Default Karlis, The .flux() method
  #2
Member
 
David P. Schmidt
Join Date: Mar 2009
Posts: 70
Rep Power: 8
schmidt_d is on a distinguished road
Karlis,

The .flux() method takes the face fluxes that come from the off-diagonal terms of the equation, in this case pEqn, and returns them directly. An easier-to-understand example would be if I were doing the continuity equation, where rhoEqn is:

fvm::ddt(rho) + fvc::div(phiv,rho)

where phiv is the velocity interpolated to cell faces and dotted with the face normals.

after solving, rhoEqn.flux() would give you the mass flux out of each cell face. Similarly, pEqn.flux() gives you the momentum flux due to the fvm:: terms of the pressure equation.

-DPS
ps. The ddtPhiCorr is a mysterious term that attempts to correct for temporal error in the flux...can't help you there.
schmidt_d is offline   Reply With Quote

Old   February 19, 2008, 14:21
Default Good evening David! >.flux(
  #3
kar
Senior Member
 
Kārlis Repsons
Join Date: Mar 2009
Location: Latvia
Posts: 111
Rep Power: 8
kar is on a distinguished road
Good evening David!

>.flux() method takes the face fluxes that come from the off-diagonal terms of the equation

Why it's necessary to distinguish between matrix diagonal and off-diagonal elements?

What papers and www would you suggest to understand this kind of things?

K.
kar is offline   Reply With Quote

Old   February 20, 2008, 06:20
Default Hi Karlis Matrix diagonal e
  #4
Senior Member
 
Join Date: Mar 2009
Posts: 248
Rep Power: 9
jaswi is on a distinguished road
Hi Karlis

Matrix diagonal elements are the elements for which you are seeking solution and off-diagonal elements are those which will effect this solution.

Checkout the basic Finite Volume, SIMPLE, PISO formulations in this book:

1) An Introduction to CFD: The Finite Volume Method by Versteeg, Malalasekera.

2) CFD by Anderson

With Best Regards
Jaswi
jaswi 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
IcoFoam aap OpenFOAM Running, Solving & CFD 15 May 28, 2012 08:30
Density in icoFoam Densidad en icoFoam manuel OpenFOAM Running, Solving & CFD 8 September 22, 2010 04:10
Possible bug in icoFoam msrinath80 OpenFOAM Bugs 6 November 19, 2007 18:35
IcoFoam on AIX 53 ds2taieb OpenFOAM Installation 1 March 24, 2006 04:22


All times are GMT -4. The time now is 20:42.