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Flow pattern induced instability in a vertical duct.

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Old   July 31, 1999, 02:10
Default Flow pattern induced instability in a vertical duct.
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Ajit D.Kulkarni
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Please let me know the liteature available on above topic.
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Old   August 2, 1999, 12:21
Default Re: Flow pattern induced instability in a vertical duct.
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Patrick Godon
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Hi there,

It is not clear from the question exactly what kind of flow and duct are involved in the problem.

Are you interested in the flow escaping from a vertical duct (like the smoke coming out of chemney)? Then basically what you have is a kind of jet. Do you have buoyancy effects too? The jet by itself is unstable to a shearing (Kelvin-Helmholtz) instability on its surface boundary with the ambient flow, which eventually can lead to turbulence. Then you first will have a wavy-like pattern. If the buoyance effects are also taken into account then you will have in addition a Rayleigh-Taylor instability that makes the flow go upwards (really like a smoke).

Or are you rather interested in the flow inside the duct itself? and instability due to the boundaries of the duct and (again) the buoyancy ?

If you could be more specific, that would help to understand exactly what is the flow problem.

PG.
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