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Old   February 25, 2011, 08:20
Question simpleFoam Basics
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Andreas P
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Hi everyone!

I'm just starting to use OF and have made some good progress with running a few tutorial cases, but currently I am stuck with some simpleFoam basics...

1.) How do I specify a stopping criterion for the steady state solver? Is it just by
Code:
convergence 1e-5
in system/fvSolution? Or are there any more options like that?

2.) To which residual does the above mentioned convergence statement refer? Velocity residual? Pressure resiual? Turbulence quantities?

3.) Which role does number of time steps play, if I specify this stopping criterion? Will it be the maximum number after which the solver is stopped, even if the desired residual has not been reached? Or doesn't it have an effect at all?

4.) How do I actually monitor the residual? Sure, OF does quite some printing to the console during the solution process. But is that really the only way to obtain convergence history data? In order to plot the residual over iterations, I would have to extract the numbers from stdout by cat/sed whatsoever. I can't really imagine that this is how everyone else does it...?

5.) Where can I find more information on the different solver specific numerical parameters (e.g. like the convergence statement in simpleFoam)?

I have already searched this forum quite a bit, but haven't really found satisfying answers... so I'd really appreciate any help!

Andreas
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Old   February 28, 2011, 09:09
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Santiago Marquez Damian
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Hello,

1,2, 3 and 5) Until I know there is no way to automatically stop a steady running checking the residuals like the "Check convergence" check box in Fluent. You have to set the appropriate number of iterations (pseudo time-steps) in order to reach your desired residuals. One have to set a criterion for each equation residual.

4) You have some utilities to do so in pyFoam package, but a I prefer a simpler way, check this thread

Plotting residuals

Regards.
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