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stability of converging flow

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Old   October 16, 2001, 07:59
Default stability of converging flow
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Bo Busk Jensen
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Hallo All

I am trying to model a converging flow between two parallel discs. The flow concides in the centre and leaves through a hole in one of the discs. My question is: Hoow is the stability of this flow?? Will it be axis symmetrical around the centre axis og the discs or will it start rotating???

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Bo
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Old   October 16, 2001, 14:58
Default Re: stability of converging flow
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John C. Chien
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(1). In theory, if the inflow is radial, then the outflow should not have the tangential component, because of angular momentum conservation. Flow acceleration is normally stable in this case. (2). In real test, you have influence of the earth gravitational and rotational field. So, it is hard to eliminate the inflow rotation. (3). Also, the small perturbation in inflow condition can be magnified easily at the center with raducing radius. Thus, it likely to have swirl component. (4). If the inflow is radial, then axisymmetric formulation could be used. In that case, it will be symmetric all the time. Even in 3-D, I think, it is still possible, if your method is good. If the formulation is in Cartesian, while the geometry is symmetric, then I think, there is no guarantee that the flow will be symmetric with no swirl.(numerical errors)
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Old   October 17, 2001, 02:38
Default Re: stability of converging flow
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Bo Busk Jensen
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Thanks John

Is it possible that you could give me a reference containing information about this?? I need for a paper I am writing.

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Bo
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