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Karman vortex - steady state solution with RANS ? |
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#1 |
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Hi,
I am wondering if I can get a steady simulation of a karman vortex simulation? So in reality this phenomenon is highly unsteady. But in my CFD I am not interested to see the vortex. I am interested in getting a steady state solution. Is this possible with RANS? If I look at this video: https://www.youtube.com/watch?v=57-URbKeWME I think I will always see some vortex and vortex detachment, even in a RANS? So if I am interested in an steady solution I should calculate maybe with URANS and take the mean of my velocities over time? Thank you for your help Cellzone |
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#2 | |
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Filippo Maria Denaro
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Quote:
Yes, the RANS formulation is based on a statistically averaging that makes the solution steady. In a similar way, you could consider the example of the laminar vortex shedding with alternating vortices. If you perform explicitly the time average of the transient solution, you will get a steady solution with two symmetric vortices. |
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#3 |
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Uwe Pilz
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RANS eliminates (real) turbulence, but ist dies not eliminate vortices at all. You may use for your task.
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Uwe Pilz -- Die der Hauptbewegung überlagerte Schwankungsbewegung ist in ihren Einzelheiten so hoffnungslos kompliziert, daß ihre theoretische Berechnung aussichtslos erscheint. (Hermann Schlichting, 1950) |
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#5 |
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Filippo Maria Denaro
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RANS means one solves always the statistically steady averaged variable, URANS introduces a time variation of the mean variable. However that does not mean that the two formulations are similar in the modelling.
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