Abstract

Temporal fluctuations in a closed turbulent shear flow with constant Reynolds number were measured. The temporal dynamics and statistical behaviors of the fluctuations in a two-decade Reynolds number set-up were analyzed in detail. Nontrivial power fluctuations were observed over a wide range of amplitudes, encompassing coherent motions over the entire system size. Results show that averaging the independent subsystems does not produce power fluctuations, the probability density function is non-Gaussian, and the power density fluctuation is independent of the Reynolds number. The relative intensity of fluctuations decreases very slowly with increasing Reynolds number.