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 February 18, 2008, 15:59 Hi! U = rUA*UEqn.H(); phi #1 Senior Member   Kārlis Repsons Join Date: Mar 2009 Location: Latvia Posts: 111 Rep Power: 17 Hi! U = rUA*UEqn.H(); phi = (fvc::interpolate(U) & mesh.Sf()) + fvc::ddtPhiCorr(rUA, U, phi); What fvc::ddtPhiCorr(rUA, U, phi) is there for? if (nonOrth == nNonOrthCorr) { phi -= pEqn.flux(); } And what ".flux()" is returning? Kārlis

 February 19, 2008, 12:47 Karlis, The .flux() method #2 Member   David P. Schmidt Join Date: Mar 2009 Posts: 71 Rep Power: 17 Karlis, The .flux() method takes the face fluxes that come from the off-diagonal terms of the equation, in this case pEqn, and returns them directly. An easier-to-understand example would be if I were doing the continuity equation, where rhoEqn is: fvm::ddt(rho) + fvc::div(phiv,rho) where phiv is the velocity interpolated to cell faces and dotted with the face normals. after solving, rhoEqn.flux() would give you the mass flux out of each cell face. Similarly, pEqn.flux() gives you the momentum flux due to the fvm:: terms of the pressure equation. -DPS ps. The ddtPhiCorr is a mysterious term that attempts to correct for temporal error in the flux...can't help you there. fumiya, mo.houssami, sharonyue and 1 others like this.

 February 19, 2008, 13:21 Good evening David! >.flux( #3 Senior Member   Kārlis Repsons Join Date: Mar 2009 Location: Latvia Posts: 111 Rep Power: 17 Good evening David! >.flux() method takes the face fluxes that come from the off-diagonal terms of the equation Why it's necessary to distinguish between matrix diagonal and off-diagonal elements? What papers and www would you suggest to understand this kind of things? K.

 February 20, 2008, 05:20 Hi Karlis Matrix diagonal e #4 Senior Member   Join Date: Mar 2009 Posts: 248 Rep Power: 18 Hi Karlis Matrix diagonal elements are the elements for which you are seeking solution and off-diagonal elements are those which will effect this solution. Checkout the basic Finite Volume, SIMPLE, PISO formulations in this book: 1) An Introduction to CFD: The Finite Volume Method by Versteeg, Malalasekera. 2) CFD by Anderson With Best Regards Jaswi