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두꺼운 난류경계층 내부에 놓인 직사각형 프리즘 주위의 유동구조
김경천,지호성,추재민,이석호,성승학,Kim, Gyeong-Cheon,Ji, Ho-Seong,Chu, Jae-Min,Lee, Seok-Ho,Seong, Seung-Hak 대한기계학회 2002 大韓機械學會論文集B Vol.26 No.4
Flow structures around a rectangular prism have been investigated by using a PIV(Particle Image Velocimetry) technique. A thick turbulent boundary layer was generated by using spires arid roughness elements. The boundary layer thickness, displacement thickness and momentum thickness were 650mm, 117.4mm and 78mm, respectively. The ratio between the model height(40mm) and the boundary layer thickness H/$\delta$, was 0.06. The Reynolds number based on the free stream velocity and the height of the model was 7.9$\times$10$^3$. The PIV measurements were performed at three different wall normal planes. Three recirculation regions at forward facing step, top of the roof and backward facing step are clearly seen and show three dimensional features. Dramatic changes of flow patterns are observed in the wake regions in the different spanwise wall normal planes. Instead of reattachment and recirculation zone, rising streamlines are depicted at the normal planes near the side wall due to the interaction with a rising horse shoe vortex. The peak of turbulent kinetic energy occurs at the separation bubble on top of the roof and the magnitude is 2.5 times higher compared with that of the wake region.
다중평면 PIV측정에 의한 저층건물 주위의 유동특성 규명
지호성(Ho Seong Ji),추재민(Jae Min Choo),김경천(Kyung Chun Kim) 대한기계학회 2001 대한기계학회 춘추학술대회 Vol.2001 No.9
Flow structures around a rectangular prism have been investigated by using a PIV(Particle Image Velocimetry) technique. A thick turbulent boundary layer was generated by using spires and roughness elements. The boundary layer thickness, displacement thickness and momentum thickness were 650㎜, 117.4㎜ and 78㎜, respectively. The ratio between the model height(40㎝) and the boundary layer thickness H/δ, was 0.06. The Reynolds number based on the free stream velocity and the momentum thickness was 1.34×10⁴. The PIV measurements were performed at three different wall normal planes. Three recirculation regions at forward facing step, top of the roof and backward facing step are clearly seen and show three dimensional features. Dramatic changes of flow patterns in the wake regions in different spanwise wall normal planes are depicted. Instead of reattachment and recirculation, rising streamlines are observed at the normal planes near the side wall due to the interaction with a rising horse shoe vortex. The peak of turbulent kinetic energy occurs at the separation bubble on top of the roof and the magnitude is 2.5 times higher compared with that of the wake region.