# FvVectorMatrixresidual before solving

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 January 28, 2007, 12:02 Hi all, I need to check conv #1 Member   cosimo bianchini Join Date: Mar 2009 Location: Florence, Tuscany, Italy Posts: 88 Rep Power: 10 Sponsored Links Hi all, I need to check convergence behavior of my calculations using root-mean-square residuals. What I need is to calculate residuals before (and after) solving the fvMatrix. fvVectorMatrix UEqn ( fvm::div(phi, U) // - fvm::Sp(fvc::div(phi), U) + turbulence->divRhoR(U) == -fvc::grad(p) ); UEqn.relax(); vectorField U_residual = UEqn.residual(); scalarField u_residual = U_residual.component(0); Info << " Normalized Initial U L2 Residuals : " << Foam::sqrt(sum(sqr(u_residual*massIn/uin))) << endl; UEqn.solve(); U_residual = UEqn.residual(); Info << " Normalized Initial U L2 Residuals : " << Foam::sqrt(sum(sqr(u_residual*massIn/uin))) << endl; ------- This structure works fine for fvScalarMatrix such as hentalpy,omega,k but fails in case of fvVectorMatrix: solution varies in case I calculate residuals before solving or not. Is there anyone that ever notice such a behavior? To my knowledge residual calculation does not change the matrix and so the solution. I looked up in the fvMatrixsolve.H at the implementation of the member residual and it doesn't seem (I have to tell that I'm not a master in reading FOAM yet) to modify the fvVectorMatrix. Is fvVectorMatrix.residual() influencing somehow the coefficients, is it just a bug or am I getting mad? I hope I have been clear enough to be understood. Thanks a lot for your answers Cosimo __________________ Cosimo Bianchini Ergon Research s.r.l. Via Panciatichi, 92 50127 Florence - ITALY Tel: +39 055 0763716 Mob: +39 320 9460153 e-mail: cosimo.bianchini@ergonresearch.it URL: www.ergonresearch.it

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