# Probable bug with laplacian steady state

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 November 23, 2009, 09:53 Probable bug with laplacian steady state #1 New Member   Valerio Novaresio Join Date: Mar 2009 Location: Polonghera, Cuneo, Italy Posts: 27 Rep Power: 9 Hi foamers... I noticed this stange behaviour with OpenFOAM. I've built a solver that only solve the laplacian (steady state version of laplacianFoam). I've tested this solver with the cavity geometry (icoFoam folder) where I set the boundaries value of my field in this way: FixedWalls: zeroGradient movingWall: fixedValue uniform 1 InternalField: fixedValue uniform 1 The analitic solution of this problem is that values of the field converged to the value 1, so in this case the initial solution correspond to the exact solution. The expected behaviour is that at first "time" step the solver of the linear system only does one (or zero) step and the convergence is achived. But, even if the correct solution is achived, the solvers needs many iterations and the initialResidual value doesn't decrese. I've tried many experiment with different initial values and my oppinion is that ther is a converging problem to the uniform solution. Someone can say me why? __________________ ...The best way to acquire new knowledge is to share it...

 November 23, 2009, 20:31 #2 Senior Member   Alberto Passalacqua Join Date: Mar 2009 Location: Ames, Iowa, United States Posts: 1,907 Rep Power: 27 Ciao Valerio, did you try to run the case with the original laplacianFoam? It should give you a set of lines with initial and final residuals equal to zero. The solution to that problem is always identical to the initial condition since all the fluxes are zero (on fixedWalls by default, and due to the equal value of T on movingWall and inside the system), as a consequence the initial residual should be zero also in the unsteady case. How did you code the steady solver? P.S. I'm Italian too __________________ Alberto Passalacqua GeekoCFD - A free distribution based on openSUSE 64 bit with CFD tools, including OpenFOAM. Available as in both physical and virtual formats. OpenQBMM - An open-source implementation of quadrature-based moment methods. To obtain more accurate answers, please specify the version of OpenFOAM you are using.

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