(458i) Coriolis-Induced Redistribution of Turbulent Kinetic Energy and Atmospheric Scintillations

In spanwise fully-developed rotating channel flows, the coupling between the Coriolis acceleration and the fluctuating velocity causes the primary and the secondary normal Reynolds momentum flux differences to flip signs in the outer region on the high pressure side of the symmetry plane.  This redistribution of energy by the Coriolis acceleration occurs in a region where the intrinsic mean vorticity is zero.  

In this presentation, the dispersion of a passive additive within the zero intrinsic vorticity region will be discussed. For low rotation numbers, the theory shows that the transverse component of the passive additive flux is mitigated by a coupling between the shear component of the Reynolds stress and the longitudinal component of the mean passive additive flux. At high rotation numbers, the dispersion coefficient in the transverse (cross flow) direction is four times larger than the dispersion coefficient in the spanwise direction. Surprisingly, the dispersion coefficient in the longitudinal direction is relatively small.

It is noteworthy that a Coriolis-induced anisotropy in the index-of-refraction of the atmosphere may provide a practical means to determine the relative latitude and the relative longitude between two fixed points on the surface of the Earth. Thus, atmospheric scintillation phenomenon may be an essential component in the mechanics of bird orientation and navigation.

Koppula, K.S., S. Muthu, A. Bénard, and C. A. Petty 2013, “The URAPS closure for the normalized Reynolds stress”, Physica Scripta, to appear June 2013. 

Koppula, K.S., A. Bénard, and C. A. Petty, 2011, “Turbulent Energy Redistribution in Spanwise Rotating Channel Flows”, Ind. Eng. Chem. Res., 50 (15), 8905-8916.

Koppula, K. S., A. Bénard, and C. A. Petty, 2009, “Realizable Algebraic Reynolds Stress Closure”, Chem. Eng. Sci., 64, 4611-4624.