Definitions for Initial and Final Residuals
 

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

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