# Definitions for Initial and Final Residuals

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 July 15, 2010, 18:09 Definitions for Initial and Final Residuals #1 New Member   Patrick Join Date: Feb 2010 Posts: 10 Rep Power: 9 Dear FOAMers I am trying to learn the importance of initial and final residuals. Is there any place where I can get their definitions? I am learning to use simpleFoam to solve simple problems like internal flow over through a pipe with sudden expansion. For low Re (~300) both the initial and final residuals drop to 1e-6. But when I triple the Re (~1000), the initial residual stay at ~0.002 range while the final residual drops to 1e-7. Irrespective of the problem, If I want to say the solution is converged, how low should the initial residuals go? Thanks

 July 16, 2010, 03:55 #2 New Member   Join Date: May 2010 Location: Cologne Posts: 27 Rep Power: 9 hi patrick, the initial residuals are the important ones, by default the residuals must be lower than 10^-5 that the simulation is converged. The final residuals are the residuals in the current step after n-iterations -> No Iterations n with pyFoamPlotWatcher you can visualise the initial residuals. http://openfoamwiki.net/index.php/Contrib_PyFoam regards elham usefi likes this.

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