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NUMERICAL INSTABILITY OVER THE SWIRLING VANES

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Old   February 8, 2005, 14:34
Default NUMERICAL INSTABILITY OVER THE SWIRLING VANES
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Dan
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Hi!

Has anyone observed the numerical instability over the swirling vanes. What we have is the flow over a set of vanes. We have pressure inlets and one pressure outlet. What we are observing is the mass flow rate through the pressure outlet is oscillating in a sinusoidal fashion.

Has anyone come across this kind of situation and has any comments/suggestions. We have tried with lowering the under relaxation factors. Even to a small number like 0.001, the mass flow rate is still sinusoidal.
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Old   February 8, 2005, 16:48
Default Re: NUMERICAL INSTABILITY OVER THE SWIRLING VANES
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Jim_Park
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Are you doing a transient or steady state calculation. By that I mean, are you solving

dq/dt = RHS

or

RHS = 0?

Asked another way: are you sure that your problem doesn't actually have a periodic (shedding) solution?
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Old   February 9, 2005, 09:12
Default Re: NUMERICAL INSTABILITY OVER THE SWIRLING VANES
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Dan
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I am using RHS=0

It is solved in steady state
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