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Turbulence and Shear Flow Phenomena -1 First International Symposium

ISBN:
1-56700-135-1 (Print)

THREE-DIMENSIONAL STRUCTURE OF SHEDDING VORTICES BEHIND A V-GUTTER

Takeshi Saito
Department of Mechanical Engineering, Kobe University Rokkodai, Nada, Kobe 657-8501, JAPAN

Naoshi Kuratani
Department of Mechanical Engineering, Kobe University Rokkodai, Nada, Kobe 657-8501, JAPAN

Yuji Ikeda
Graduate School of Science and Technology, Kobe University, Kobe, Japan

Tsuyoshi Nakajima
Department of Mechanical Engineering Kobe University Rokkodai, Nada, Kobe 657-8501, JAPAN

Abstract

Flow visualization and particle image velocimetry (PIV) measurements were performed to reveal the three-dimensional structure of high frequency vortex shedding behind a V-gutter.
Tubular structures connecting adjacent vortices were found in front of the shedding vortex in the visualization image. PIV measurements permitted quantification of these tubular structures, although there were many errors in the results of these measurements. The overlap and moving average methods were applied to PIV-measured velocities to increase spatial resolution and to reduce errors. It was shown that the vortex shedding pattern behind a V-gutter forms into streamwise structures. The streamwise vorticity reached 20% to 100% of the spanwise vorticity at the same location. An FFT (Fast Fourier Transform) analysis was performed using the PIV data to determine the streamwise vorticity scale. This resulted in a calculated vortex diameter of 5mm, and this was verified by measurements taken from the visualization images.