Shear dispersion and turbulence decorrelation by differential rotation

O.E. Garcia, N.H. Bian

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    The shear enhanced dispersion of a passive scalar field subject to differential rotation is investigated analytically and interpretations are given in terms of turbulence shear decorrelation. Using the method of advected coordinates, the enhanced dispersion caused by steady and oscillatory flows with uniform shear is derived and the well-known turbulence shear decorrelation theory is recovered. The additional role of kinetic energy transfer due to differential advection of vorticity is also pointed out. Finally, the shear enhanced dispersion due to flows with periodic variations in space as well as time is given. It is found that radially alternating flows may significantly reduce the turbulence decorrelation time provided the root mean square flow shear is larger than the flow oscillation frequency. In the opposite limit of fast flow oscillations there is no turbulence decorrelation. (C) 2005 American Institute of Physics.
    Original languageEnglish
    JournalPhysics of Plasmas
    Issue number1
    Pages (from-to)014503
    Number of pages4
    Publication statusPublished - 2005

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