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1 FAST - Fluides, automatique, systèmes thermiques 2 SPHYNX - Systèmes Physiques Hors-équilibre, hYdrodynamique, éNergie et compleXes SPEC - UMR3680 - Service de physique de l-état condensé, IRAMIS - Institut Rayonnement Matière de Saclay

Abstract : What is the turbulent drag force experienced by an object moving in a rotating fluid? This open and fundamental question can be addressed by measuring the torque needed to drive an impeller at constant angular velocity ω in a water tank mounted on a platform rotating at a rate Ω. We report a dramatic reduction in drag as Ω increases, down to values as low as 12% of the non-rotating drag. At small Rossby number Ro = ω-Ω, the decrease in drag coefficient K follows the approximate scaling law K ∼ Ro, which is predicted in the framework of nonlinear inertial wave interactions and weak-turbulence theory. However, stereoscopic particle image velocimetry measurements indicate that this drag reduction rather originates from a weakening of the turbulence intensity in line with the two-dimensionalization of the large-scale flow.





Author: Antoine Campagne - Nathanaël Machicoane - Basile Gallet - Pierre-Philippe Cortet - Frédéric Moisy -

Source: https://hal.archives-ouvertes.fr/



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