Study on the Flow Characteristics of Horseshoe Vortex System near the Juncture of a Rectangular pillar

• Main Authors: Chin-Wei Chen, 陳謹偉
• Other Authors: Chang Lin
• Format: Others
• Language: zh-TW
• Published: 2000
• Online Access: http://ndltd.ncl.edu.tw/handle/12147008983007290826

碩士 === 國立中興大學 === 土木工程學系 === 88 === The laminar boundary layer on the wall ahead of a vertical rectangular pier is in a region of adverse pressure gradient, and within some distance upstream of the body this boundary layer experiences a three-dimensional separation. In the separated region, a system of vortices is developed and stretched around the base of the body like a horseshoe shape. The characteristics of horseshoe vortex system near the juncture of a vertical rectangular pier and a horizontal bottom was studied experimentally using particle image velocimetry (PIV), fiber laser Doppler velocimetry (FLDV), and particle tracking flow visualization technique. The purpose of the present study is to provide the most comprehensive classification and description of the range of horseshoe vortex system. Moreover, the characteristics of the steady type and regular type are pointed out in the present study. Several detailed flow structures in the steady type and breakaway type, regarding the position of primary vortex core, the vortex velocity profile, and the frequency of horseshoe vortex reconstruction are discussed. The range of the Reynolds number Re, based upon the free stream velocity (U0 ) and the width of vertical rectangular pier (W), is form 1200 to 8500.