Noise correlations in shear flows |
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| Authors: | B Eckhardt R Pandit |
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| Institution: | 1.Fachbereich Physik, Philipps-Universit?t Marburg, 35032 Marburg, Germany,DE;2.Centre for Condensed Matter Theory, Department of Physics, Indian Institute of Science, Bangalore, 560 012, India,IN |
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| Abstract: | We consider the effects of a shear on velocity fluctuations in a flow. The shear gives rise to a transient amplification that
not only influences the amplitude of perturbations but also their time correlations. We show that, in the presence of white
noise, time correlations of transversal velocity components are exponential and that correlations of the longitudinal components
are exponential with an algebraic prefactor. Cross correlations between transversal and downstream components are strongly
asymmetric and provide a clear indication of non-normal amplification. We suggest experimental tests of our predictions.
Received 26 February 2002 / Received in final form 11 March 2003 Published online 20 June 2003
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ID="a"e-mail: bruno.eckhardt@physik.uni-marburg.de
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ID="b"Also at: Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore, India |
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| Keywords: | PACS 47 27 -i Turbulent flows convection and heat transfer – 05 40 Ca Noise – 47 20 Ft Instability of shear flows |
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