Transition to turbulence behind a traveling plate

Journal article (2023)

Authors

J. Reijtenbagh Fluid Mechanics - Mechanical, Maritime and Materials Engineering
J. Westerweel Fluid Mechanics - Mechanical, Maritime and Materials Engineering
W. van de Water Fluid Mechanics - Mechanical, Maritime and Materials Engineering
Research Group
Fluid Mechanics (Mechanical, Maritime and Materials Engineering) (TU Delft)
Copyright: © 2023 J. Reijtenbagh, J. Westerweel, W. van de Water
DOI
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https://doi.org/10.1103/PhysRevFluids.8.104601
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Published Date

2023

Language

English

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Faculty

Mechanical, Maritime and Materials Engineering

Department

Process and Energy

Research Group

Fluid Mechanics

Abstract

In our experiment a vortical flow behind a traveling plate turns into turbulence. By exactly repeating this experiment 42 times with a robot, we study the statistics of this transition. In each realization the fate of the flow is followed over 1.7 s when the plate travels with a constant velocity. It suddenly turns turbulent at a scaled traveled distance of x∗≈5.5. We register the vorticity in a plane that divides the plate perpendicularly. We introduce an original Lagrangian measure of variability between the experiment realizations. The finite-time Lyapunov exponent field of a single experiment predicts this variability; thus we confirm ergodicity. Apart from pointwise measures, yielding a distribution over the field of view, we study the statistics of the circulation computed over the upper and lower half of the domain. The almost perfect symmetry both of the mean and of the fluctuations points to their origin as the fluctuating vortex ring trailing behind the plate. During the initial phase long-time correlations exist in the flow, but they cease once the flow turns turbulent. By ordering our repeated experiments we find that extreme circulations are preceded by circulations that are larger than the median.