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Is it normal for an unsteady simulation to appear steady initially?

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Old   November 27, 2020, 12:02
Question Is it normal for an unsteady simulation to appear steady initially?
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Bradley Craig
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As the title says.



I am running a 2D turbulent, unsteady simulation of a simple cylinder as a test case using a 2nd order dual time stepping method and after a large number of iterations in the problem doesnt seem to be dispaying any unsteady flow characteristics.


Is this transient behaviour to be expected initially?


Thanks in advance
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Old   November 28, 2020, 11:20
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Pedro Gomes
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What unsteady phenomena are you expecting to capture?
You will not see turbulence eddies with a URANS simulation...
Another possibility is that your timestep is too large for what you are simulating (vortex shedding?) and so everything get's damped.
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Old   November 28, 2020, 13:33
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Bradley Craig
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I was expecting to see vortex shredding, but instead i just obtain a fully developed, constant wake behind the cylinder.


I will try decreasing the timestep to see if this will show signs of vortexes.


Thank you
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cylinder, structured mesh., unsteady flow, urans

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