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

Continuity Equation rhoEqnH

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

Reply
 
LinkBack Thread Tools Display Modes
Old   July 17, 2007, 17:49
Default Hi all I am interested in com
  #1
New Member
 
morteza
Join Date: Mar 2009
Posts: 18
Rep Power: 8
morteza is on a distinguished road
Hi all
I am interested in compressible solvers (rhoTurbFoam,coodles,...).
As one of these solvers is used we have below line for rhoEqn solving:

diagonal: Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0

My question is about the zero values of Initial residual,Final residual and number of iterations.

Is rhoEqn.H solved? If yes, why we don't have any iterations and if no, why it doesn't solve.

Thanks in advance
Morteza
morteza is offline   Reply With Quote

Old   July 17, 2007, 17:56
Default The matrix is diagonal and rig
  #2
Senior Member
 
Hrvoje Jasak
Join Date: Mar 2009
Location: London, England
Posts: 1,758
Rep Power: 21
hjasak will become famous soon enough
The matrix is diagonal and right-hand-side only. You don't need a solver, just divide the rhs with the diagonal: that's how you get no residual and no iterations.

In fact, initial residual is non-zero, but calculating it would be a waste of time...

Enjoy,

Hrv
__________________
Hrvoje Jasak
Providing commercial FOAM/OpenFOAM and CFD Consulting: http://wikki.co.uk
hjasak is offline   Reply With Quote

Old   September 5, 2007, 23:16
Default Hello there, I'm interested i
  #3
Member
 
Richard Kenny
Join Date: Mar 2009
Posts: 59
Rep Power: 9
richpaj is on a distinguished road
Hello there,
I'm interested in the solution procedure for diesel foam.

In the file YEqn.H it appears that all the mass fractions of the component
species are solved for, as is the continuity equation (rhoEqn.H) for the
averaged density of the mixture.

Is the constraint that the "sum of Yi == 1" not implemented at some point
in the solver? Or equivalently, deriving one Yi from the sum of the rest?

The output in the logfile of the diesel foam case directory indicates the residuals
of each species but, I wonder if these are made with reference to the above constraint.

Many thanks if you've time to clear up this point,

Regards,

Richard K
richpaj is offline   Reply With Quote

Old   September 5, 2007, 23:28
Default Come to think of it, Yi are on
  #4
Member
 
Richard Kenny
Join Date: Mar 2009
Posts: 59
Rep Power: 9
richpaj is on a distinguished road
Come to think of it, Yi are only the gaseous components.
There's no constraint to apply.

I read too much into the original reference.

R. K.
richpaj 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
Continuity equation selim CFX 1 November 20, 2007 12:04
Continuity Equation selim Main CFD Forum 12 October 27, 2007 15:14
Continuity Equation selim CFX 8 October 26, 2007 10:51
continuity equation Rafal Main CFD Forum 4 November 29, 2006 10:27
Poisson equation vs continuity equation DJ Main CFD Forum 1 August 5, 2004 20:01


All times are GMT -4. The time now is 07:44.