TITLE:
Unsteady Behavior of Necklace Vortex Produced by a Square Plate Protrusion
AUTHORS:
Keita Toda, Tsukasa Haraoka, Teruyoshi Sadahiro, Hidemi Yamada
KEYWORDS:
Necklace Vortex, Unsteady Flow, Square Plate, Visualization, PIV Analysis
JOURNAL NAME:
Open Journal of Fluid Dynamics,
Vol.8 No.1,
March
29,
2018
ABSTRACT: In this study, the unsteady behavior of necklace vortices formed in front of a square flat plate was experimentally investigated by flow visualization and PIV analysis by using a water channel. As a result, the necklace vortices started to oscillate when the Reynolds number increased beyond approximately 2000. Then, an amalgamation behavior of the necklace vortices took place when the Reynolds number increased beyond approximately 2650. Furthermore, in the same Reynolds number range, a breakaway behavior appeared when the relative height of the square plate was beyond approximately h/δ = 4.0. The features of the necklace vortices behaviors in the oscillation, amalgamation and breakaway states were explained by observing the time-series image of path lines and by analyzing the frequency of velocity fluctuation.