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Old   November 29, 2006, 08:33
Default URANS
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Magic
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I am going to perform the Unsteady RANS simulation to analyze cavity flow oscillations. I have no idea about the time step. I will be grateful if some one could tell me how can I choose the time step for the first order implicit time advancing.

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Old   November 29, 2006, 09:55
Default Re: URANS
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ag
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Determine the oscillation frequencies of the cavity using Rossiter's formula. For the highest frequency you want to try to capture, plan on 50-100 timesteps per period. Back out the timestep. Using URANS you'll be lucky to get the second harmonic, so there's no point in going to a much higher frequency. And first-order time is not a good choice for simulating unsteady flows - you really need to use second-order time differencing.
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Old   November 30, 2006, 05:31
Default Re: URANS
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Mar
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In addition

If these calculations will be used to exstimate noise--> RANS is not the best way ....
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Old   November 30, 2006, 11:10
Default Re: URANS
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Magic
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Thanks to all of you.
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