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ON MULTISCALE ACCELERATION STATISTICS IN ROTATING AND SHEARED HOMOGENEOUS TURBULENCE

Frank G. Jacobitz
Mechanical Engineering Program University of San Diego 5998 Alcala Park San Diego, California 92110, USA

Kai Schneider
Laboratoire de Modélisation et Simulation Numérique en Mécanique, CNRS et Universités d'Aix-Marseille & CMI, Université de Provence, 39 rue Frédéric Joliot-Curie, 13453 Marseille, France

Wouter J. T. Bos
LMFA-CNRS Ecole Centrale de Lyon - University de Lyon 36 Avenue Guy de Collongues, 69134 Ecully Cedex, France

Marie Farge
LMD-IPSL-CNRS Ecole Normale Superieure 24 rue Lhomond, 75231 Paris Cedex 5, France

Abstract

The acceleration statistics of sheared and rotating homogeneous turbulence are studied using direct numerical simulation results with different rotation ratios of Coriolis parameter to shear rate f / S. For the range of rotation ratios 0 ≤ f / S ≤ 1, a destabilization of the flow due to rotation and growth of the turbulent kinetic energy is obtained. For other values of f / S, rotation stabilizes the flow and a decay of the turbulent kinetic energy is observed. The statistical properties of Lagrangian and Eulerian acceleration are considered and the influence of the rotation ratio and the scale dependence of the statistics is investigated. The probability density functions (pdfs) of both Lagrangian and Eulerian acceleration show a strong and similar dependence on the rotation ratio. The flatness further quantifies its dependence and yields values close to three for strong rotation. For moderate and vanishing rotation, the flatness of the Eulerian acceleration is larger than that of the Lagrangian acceleration, contrary to previous results for isotropic turbulence. A wavelet-based scale-dependent analysis shows that the flatness of both Eulerian and Lagrangian acceleration increases as scale decreases. For strong rotation, the Eulerian acceleration is more intermittent than the Lagrangian acceleration, while the opposite result is obtained for moderate rotation.