convergence in OpenFoam

cleoo · October 24, 2016, 10:38

how do you know that your soltuion has converged?
because sometimes if it converged before the endTime it will say it has 'converged in x iterations' so does that mean if you reached you end time and it still hasn't said that it hasn't converged?

I am asking about this because I am running a transient simulation and after several hundred iterations I see no change when I look at the results, so to me I am guessing it has reached a steady state which means it converged, is this correct? and to mention, it has not reached the endTime yet

is this too trivial?

the_edge123 · July 16, 2017, 06:46

pyFoamPlotWatcher.py may help

--
Fabien

Alasir · August 25, 2017, 06:55

You may have to specify what kind of solver you are using. But assuming that you are using one that is designed to converge to a steadystate solution:

If it converges in x iterations before reaching the end time then it has reached what it belives is a steady state.

If it's not in a steady state yet, you may have to check if your convergence criteria are to relaxed.

If it's been in a steady state for a while but your simulaton is not stoping, the convergence criteria may be to strict.

If it reaches the end time then it could not find a convergent solution in the given time.

October 24, 2016, 10:38	convergence in OpenFoam	#1
cleoo Member annn Join Date: Jun 2016 Posts: 40 Rep Power: 10	how do you know that your soltuion has converged? because sometimes if it converged before the endTime it will say it has 'converged in x iterations' so does that mean if you reached you end time and it still hasn't said that it hasn't converged? I am asking about this because I am running a transient simulation and after several hundred iterations I see no change when I look at the results, so to me I am guessing it has reached a steady state which means it converged, is this correct? and to mention, it has not reached the endTime yet is this too trivial? Last edited by cleoo; October 27, 2016 at 11:14.

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July 16, 2017, 06:46		#2
the_edge123 New Member Join Date: Jul 2017 Posts: 6 Rep Power: 9	pyFoamPlotWatcher.py may help -- Fabien

August 25, 2017, 06:55		#3
Alasir Member Anders Utnes Join Date: May 2017 Location: Norway Posts: 34 Rep Power: 9	You may have to specify what kind of solver you are using. But assuming that you are using one that is designed to converge to a steadystate solution: If it converges in x iterations before reaching the end time then it has reached what it belives is a steady state. If it's not in a steady state yet, you may have to check if your convergence criteria are to relaxed. If it's been in a steady state for a while but your simulaton is not stoping, the convergence criteria may be to strict. If it reaches the end time then it could not find a convergent solution in the given time.