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

position of body force on the momentum equation

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

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   September 23, 2014, 05:48
Default position of body force on the momentum equation
  #1
lin
Senior Member
 
Hua Zen
Join Date: Mar 2009
Posts: 138
Rep Power: 15
lin is on a distinguished road
Hi, I have a question on the position of the body force on the momentum equation. I have search the forum and find two different strategy:

1. It should be included in the Ueqn:

fvVectorMatrix UEqn ( fvm::ddt(U) + fvm::div(phi, U) - fvm::laplacian(nu, U) == F );

2: It should be included in the predictor step:

solve(UEqn ==F -fvc::grad(p));

Can any expert explain to me which one is correct?
lin is offline   Reply With Quote

Old   September 26, 2014, 15:00
Default
  #2
Cyp
Senior Member
 
Cyprien
Join Date: Feb 2010
Location: Stanford University
Posts: 299
Rep Power: 16
Cyp is on a distinguished road
You can do whatever you want as far as the PISO loop is consistent.

I mean, with the first option, you don't have to change anything in the algorithm (F is part of H).

For the second option, you have to modify the recontruction of the velocity from the pressure gradient to include F.

Both options leads to the same results.

Best,
Cyp
Cyp is offline   Reply With Quote

Old   September 26, 2014, 22:31
Default
  #3
lin
Senior Member
 
Hua Zen
Join Date: Mar 2009
Posts: 138
Rep Power: 15
lin is on a distinguished road
Thanks Cyp for your help.
lin 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
impact force (shear stress) by waterjet impingement herozhu Main CFD Forum 0 May 7, 2014 21:39
Momentum by force equation in UDF tom634 Fluent UDF and Scheme Programming 0 October 18, 2013 06:14
Question on the discretization of momentum equation in icoFoam MPJ OpenFOAM 3 October 4, 2011 10:44
Constant velocity of the material Sas CFX 15 July 13, 2010 09:56
UDF Addidtional Force to momentum equation sfawal FLUENT 10 July 15, 2009 10:29


All times are GMT -4. The time now is 12:56.