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In Q-criterion method, is the value of Q representative of vortex strength? |
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#1 |
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S Banerjee
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It is known that connected regions of Q>0 represents vortices. Therefore can we think the magnitude of Q above 0 is representative of the vortex strength?
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#4 |
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S Banerjee
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#5 |
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But you are just using synonyms for the exact same wording. There is nothing mathematical or physical in that concept.
What I wanted to put forward is that, as a matter of fact, we don't have a single, clear, physical definition of what a vortex is. What we have, instead, is an ensemble of features we think should be present in what we call vortex. Q is just one of them. Quoting Lesieur: "Q>0 is a necessary condition for the existence of thin, convex low-pressure tubes [...] which are generally associated with coherent vortices". In particular, note that nothing is said on its magnitude. However, the higher is Q, the larger the local pressure Laplacian, which is a measure of the local pressure difference. |
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#6 |
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Filippo Maria Denaro
Join Date: Jul 2010
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I think we should come back to the basic definition of vortex tube as detailed by Chorin & Marsden in their textbook. Intensity of vorticity multiplied by the area section is constant.
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Tags |
q criterion, turbulence, vortex, vortex detection, vorticity |
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