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How to simulate more shedding cycles of the unsteady NACA0012 flow?

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Old   August 3, 2021, 11:16
Default How to simulate more shedding cycles of the unsteady NACA0012 flow?
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Avinash Arun
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I have been trying to simulate the unsteady flow over naca 0012 airfoil. The simulation converges and stops after 1 shedding cycle. I wish to simulate for more cycles how can I do that ?
I have attached the configuration file here.
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File Type: txt unsteady_naca0012.txt (6.9 KB, 8 views)
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Old   August 3, 2021, 16:25
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Wally Maier
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Hi A Arun,

Thanks for your question. I dont have a ton of experience in unsteady flows, but I would suggest increasing your TIME_ITER field to something longer. If the simulation is kicking out before then, you could make your convergence fields more stringent, i.e. RESIDUAL_MINVAL=-8 instead of -3. (Not sure on this one).

Let us know if that works,
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Old   August 4, 2021, 02:08
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Hi Wallym,

Thanks for the reply. In this simulation changing the convergence criteria does simulate for a longer time but not for more shedding cycles. (Like the simulation is stretched ). Changing TIME_ITER also does not reflect any change. I tried changing almost every value but im not able to simulate for more shedding cycles. I even deleted the convergence criteria.
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Old   August 4, 2021, 12:30
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Hmmmm,
How about increasing the MAX_TIME option?
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Old   August 5, 2021, 04:37
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tried that too. okay so one thing that I noticed is that it is definitely simulating for a longer period but when I use paraview to visualize the simulation the simulation stops after one shedding cycle and the remaining output files are just dummy
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Old   August 7, 2021, 06:13
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Quote:
Originally Posted by A Arun View Post
Hi Wallym,

Thanks for the reply. In this simulation changing the convergence criteria does simulate for a longer time but not for more shedding cycles. (Like the simulation is stretched ). Changing TIME_ITER also does not reflect any change. I tried changing almost every value but im not able to simulate for more shedding cycles. I even deleted the convergence criteria.
Hi Arun,

Did you try to change the time step? It is possible that the issue would be related to the inability of the code to identify the shedding cycles as they do not correspond to the vortex shedding frequency.

Hope that helps.

Ravi
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Old   August 7, 2021, 14:31
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Hi Ravi,
Thanks for the reply but changing time steps does not have any effect the simulation runs for as long as I want but when I visualize the flow field it stops after a certain point showing no change whatsoever.
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Old   May 18, 2022, 20:34
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Guangnan Jia
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Quote:
Originally Posted by A Arun View Post
I have been trying to simulate the unsteady flow over naca 0012 airfoil. The simulation converges and stops after 1 shedding cycle. I wish to simulate for more cycles how can I do that ?
I have attached the configuration file here.
Hi, Arun. Have you solved this problem yet? I faced the same problem as you now. Thanks for reply
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