Why the convergence of a steady problem also need several time evolution steps

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 June 9, 2020, 03:42 Why the convergence of a steady problem also need several time evolution steps #1 Member   Wenming Yang Join Date: Jun 2018 Posts: 42 Rep Power: 6 Dear Foamers, I found that if we solve a steady problem such as that using "simpleFoam", whereas the convergence of it also need several time steps. I am not sure if this is a general conclusion. I checked this using the tutorials of "incompressible/simpleFoam/airFoil2D" in OpenFOAM. If this is true, is it mean that we have to use two times when solving a transient problem, one is for the evolution within another time step. I am confused about this. Dose anyone has some ideas?

 June 15, 2020, 05:03 transient and steady-state: 2 & 1 time consideration respectively #2 Member   Sourav Mandal Join Date: Jul 2019 Posts: 54 Rep Power: 5 Hi, You are right, there are 2 different times to be considered in transient problem. Whereas for any steady-state only one. I have never run in the transient simulation, only have worked with steady-state problems so far. As far as I know, this stems from courant number consideration, which is important for transient but need not be considered for steady-state. I can share some links that might be useful: https://en.wikipedia.org/wiki/Couran...Lewy_condition Courant Number PS: I am new to CFD simulation, experienced users don't hesitate to correct me if I am unclear / wrong.

 June 15, 2020, 19:03 #3 Member   Wenming Yang Join Date: Jun 2018 Posts: 42 Rep Power: 6 Dear Sourav, Thank you for your reply. I am not sure with this. But there is no second time in some transients solver such as pisoFoam in OpenFOAM.

 Tags steady problems, time evolution, transient problem