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Power fluctuations in a closed turbulent shear flow
J F Pinton1, P C Holdsworth, R Labbé
1Laboratoire de Physique, CNRS UMR 5672, Ecole Normale Supérieure de Lyon, 46, allée d'Italie, 69364 Lyon Cedex 7, France.
Summary
We experimentally studied power consumption in turbulent flow. We found significant, system-wide power fluctuations that are independent of Reynolds number, suggesting critical phenomena analogies.
Area of Science:
- Fluid Dynamics
- Turbulence Research
- Statistical Physics
Background:
- Turbulent flows exhibit complex dynamics.
- Understanding energy dissipation in turbulence is crucial.
- Previous studies often focused on averaged properties.
Purpose of the Study:
- To experimentally investigate the power consumption (P) and its fluctuations in confined turbulent flow.
- To analyze the temporal dynamics and statistical properties of power consumption across two decades of Reynolds numbers (Re).
- To explore the relationship between power fluctuations, fluid motion, and analogies with critical phenomena.
Main Methods:
- Experimental setup for confined turbulent flow.
- Measurement of power consumption (P) over a range of Reynolds numbers (Re).
- Analysis of temporal dynamics, statistical properties, and probability density functions (PDF) of power fluctuations.
Main Results:
- Nontrivial power fluctuations occur with wide amplitudes, involving coherent motions across the entire system.
- Power fluctuations are not due to averaging of independent subsystems; the PDF of P is strongly non-Gaussian.
- The shape of the PDF is independent of Reynolds number, and fluctuation intensity decreases very slowly with increasing Re.
Conclusions:
- Power fluctuations in confined turbulent flow are a significant phenomenon, not an artifact of averaging.
- The observed behavior suggests an analogy with critical phenomena in statistical physics.
- Further research can explore the implications of these findings for turbulence theory and energy dissipation models.