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An extension to the universal time scale for vortex ring formation

Published online by Cambridge University Press:  12 March 2021

Raphaël Limbourg Open the ORCID record for Raphaël Limbourg [Opens in a new window]  and
Jovan Nedić Open the ORCID record for Jovan Nedić [Opens in a new window]
Raphaël Limbourg
Affiliation:
Department of Mechanical Engineering, McGill University, Montréal, QC H3A 0C3, Canada
Jovan Nedić*
Affiliation:
Department of Mechanical Engineering, McGill University, Montréal, QC H3A 0C3, Canada
*
†Email address for correspondence: jovan.nedic@mcgill.ca
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Abstract

The formation of vortex rings emanating from orifices with different orifice-to-tube diameter ratios $D_0/D_p$ is studied using time-resolved particle image velocimetry. The invariants of the motion in their non-dimensional form are computed and presented in the non-dimensional time space $t^*=U_0 t/D_0$, where the subscript 0 refers to the exhaust quantities. The classic slug-flow model is revisited and extended to account for the contraction of the flow when fluid is being pushed out through the orifice. Accordingly, a new time scale in terms of the contracted quantities (subscript $\star$) is defined as $T^*=U_\star t/D_\star$. Results show that the modified slug-flow model unifies the formation number of orifices and straight nozzles with a value of approximately 4.

JFM classification

Vortex Flows: Vortex dynamics Wakes/Jets: Jets

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Type
JFM Papers
Information
Journal of Fluid Mechanics , Volume 915 , 25 May 2021 , A46
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Copyright
© The Author(s), 2021. Published by Cambridge University Press

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References

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