# Continuity Equation rhoEqnH

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 July 17, 2007, 17:49 Hi all I am interested in com #1 New Member   morteza Join Date: Mar 2009 Posts: 18 Rep Power: 10 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

 July 17, 2007, 17:56 The matrix is diagonal and rig #2 Senior Member   Hrvoje Jasak Join Date: Mar 2009 Location: London, England Posts: 1,810 Rep Power: 25 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

 September 5, 2007, 23:16 Hello there, I'm interested i #3 Member   Richard Kenny Join Date: Mar 2009 Posts: 64 Rep Power: 11 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

 September 5, 2007, 23:28 Come to think of it, Yi are on #4 Member   Richard Kenny Join Date: Mar 2009 Posts: 64 Rep Power: 11 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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