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Misleading low Residuals long before Steady state solution is reached! |
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August 20, 2013, 07:16 |
Misleading low Residuals long before Steady state solution is reached!
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lreflow
Join Date: Jul 2013
Posts: 1
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Hello dear Foamers,
I am doing a turbulent incompressible steady state Simulation involving a porous media using porousSimpleFoam. While my pressure Residuals drop below 1e-3 after about 1000 iterations and then oscillate slightly around 5e-4 , I have obviously not reached my steady state solution at this point as can be seen in Uplot.png where the velocities at 4 points on the surface of the porous media are plotted against the iterations. Judging by the residuals alone I would have stopped the simulations way to early. I am wondering what could cause this situation where the residuals are a very bad measure of convergence? I set a low relaxation factor for the velocity following these guidelines: http://www.kxcad.net/star-ccm/online...edFlow-09.html The realizable kepsilon model was switched on after 300 iterations. I attached my checkMeshlog my fvSolution and fvSchemes file. I have to do a parameter study and if possible I would like to reduce the necessary number of iterations before starting with it. Thanks for any help and thoughts on this. Best wishes, lreflow |
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