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-   -   Continuity Equation rhoEqnH (https://www.cfd-online.com/Forums/openfoam-solving/59464-continuity-equation-rhoeqnh.html)

morteza July 17, 2007 17:49

Hi all I am interested in com
 
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

hjasak July 17, 2007 17:56

The matrix is diagonal and rig
 
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

richpaj September 5, 2007 23:16

Hello there, I'm interested i
 
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 September 5, 2007 23:28

Come to think of it, Yi are on
 
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.


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