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Definitions for Initial and Final Residuals

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Old   July 15, 2010, 18:09
Default Definitions for Initial and Final Residuals
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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?

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Old   July 16, 2010, 03:55
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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.

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