Instability of a Junction Vortex

James Allen

Laboratoire d'Etudes Aerodynamiques
Université de Poitiers

Abstract-
The flow field in the region where a moving wall slides under a stationary one produces a coherent vortical structure if the Reynolds number is large enough. Experiments were conducted in the Reynolds number range 5 · 102 – 5 · 105, where the Reynolds number develops during an experiment and is defined as Re = UL/n, where L is the distance the impulsively started wall has moved from rest and U is the wall speed. For this Reynolds number range the vortex was observed to transition from laminar behavior at Re = 13 · 103 to fully turbulent by Re = 40 · 103. Transition is marked by the formation of centrifugal instabilities on the outer turn of the primary vortex.

 


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