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

A question about UEqn.H (interPhaseChangeFoam)

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

Like Tree1Likes
  • 1 Post By abe

Reply
 
LinkBack Thread Tools Display Modes
Old   August 26, 2012, 00:24
Default A question about UEqn.H (interPhaseChangeFoam)
  #1
New Member
 
Zheng.Zhi
Join Date: Jul 2009
Location: LanZhou China
Posts: 10
Rep Power: 8
Zheng.Zhi is on a distinguished road
the UEqn.H at interPhaseChangeFoam

fvVectorMatrix UEqn
(
fvm::ddt(rho, U)
+ fvm::div(rhoPhi, U)
- fvm::Sp(fvc::ddt(rho) + fvc::div(rhoPhi), U)
- fvm::laplacian(muEff, U)
- (fvc::grad(U) & fvc::grad(muEff))
//- fvc::div(muEff*(fvc::interpolate(dev2(fvc::grad(U) )) & mesh.Sf()))
);

but the UEqn.H at interFoam

fvVectorMatrix UEqn
(
fvm::ddt(rho, U)
+ fvm::div(rhoPhi, U)
- fvm::laplacian(muEff, U)
- (fvc::grad(U) & fvc::grad(muEff))
//- fvc::div(muEff*(fvc::interpolate(dev(fvc::grad(U)) ) & mesh.Sf()))
);

I don't understand why need - fvm::Sp(fvc::ddt(rho) + fvc::div(rhoPhi), U) at interPhaseChangeFoam , Could anybody please answer me ? thanks very much.
Zheng.Zhi is offline   Reply With Quote

Old   August 26, 2012, 12:17
Default
  #2
Senior Member
 
Nima Sam
Join Date: Sep 2009
Location: Tehran, Iran
Posts: 1,124
Blog Entries: 1
Rep Power: 14
nimasam is on a distinguished road
Send a message via Yahoo to nimasam
fvm::Sp(fvc::ddt(rho) + fvc::div(rhoPhi), U)
this term would be zero mathematically because
fvc::ddt(rho) + fvc::div(rhoPhi)
is global continuity equation, and i guess it is added to consider
any numerical error in global continuity equation
nimasam is offline   Reply With Quote

Old   April 8, 2013, 07:32
Default
  #3
abe
Member
 
ABE
Join Date: Jul 2012
Posts: 37
Rep Power: 5
abe is on a distinguished road
I am agree with Nimasam. It returns the continuity equation value. I have checked the results in two conditions with and without this term. Results are fairly the same. However, I should say that by using this term it seems that the convergence speed is much better.
PS: in the OF22, this term has been removed!
dawnrain likes this.
abe is offline   Reply With Quote

Old   April 8, 2013, 07:34
Default
  #4
abe
Member
 
ABE
Join Date: Jul 2012
Posts: 37
Rep Power: 5
abe is on a distinguished road
Quote:
Originally Posted by nimasam View Post
fvm::Sp(fvc::ddt(rho) + fvc::div(rhoPhi), U)
this term would be zero mathematically because
fvc::ddt(rho) + fvc::div(rhoPhi)
is global continuity equation, and i guess it is added to consider
any numerical error in global continuity equation

Hi, have you been able to use interPhaseChange in OF21 or 22?
I can get results by previous versions (i.e. OF1.5). But by these new versions results are not good at all.


ABE
abe 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
Bug about MULES::implicitSolve for interPhaseChangeFoam in OF-1.6 chiven OpenFOAM Bugs 18 April 18, 2013 22:56
Question Re Engineering Data Source imnull ANSYS 0 March 5, 2012 14:51
internal field question - PitzDaily Case atareen64 OpenFOAM Running, Solving & CFD 2 January 26, 2011 16:26
question on bounday layer modeling Wen Long Main CFD Forum 2 November 12, 2005 18:29
Poisson Solver question Suresh Main CFD Forum 3 August 12, 2005 04:37


All times are GMT -4. The time now is 13:54.