Shape effect on flapping dynamics of an inverted flag in a uniform flow = 균일 유동 내 역방향 깃발의 플래핑 운동에 깃발 형상이 미치는 영향

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The flapping motion of inverted flags with various shapes in a uniform flow were simulated by using the immersed boundary method. The shapes of the flags were characterized in terms of the shape ratio (S = $W_T/W_L$), i.e., the ratio of the trailing edge width ($W_T$) to the leading edge width ($W_L$). To explore the effects of varying S on the flapping dynamics of inverted flags, the peak-to-peak amplitude (A/L) and the Strouhal number ($S_t$) were determined as functions of the bending rigidity (0.1 ≤ $\gamma$ ≤ 0.3) and the shape ratio (0.5 ≤ S ≤ 2). The vortical structures behind the inverted flag were visualized by using the Q-criterion to elucidate the vortex dynamics. The hydrodynamic forces exerted on each inverted flag were analyzed to find the correlation between its kinematics and vortex formation during the flapping period of the inverted flag. The strain energy ($E_s$) stored in the inverted flag and the ratio (R) of the conversion of flow kinetic energy to strain energy were also determined. Finally, we explored the effects of varying the shape ratio S' = $W_T/W_L$ while keeping the trailing edge width constant ($W_T$ = 1) instead of the area of inverted flag. The Strouhal number is maximized at S' = 1. The conversion ratio of S' = 2 is 2.5% higher than that of S' = 1.
Sung, Hyung Jinresearcher성형진researcher
Description
한국과학기술원 :기계공학과,
Publisher
한국과학기술원
Issue Date
2019
Identifier
325007
Language
eng
Description

학위논문(석사) - 한국과학기술원 : 기계공학과, 2019.2,[iv, 26 p. :]

Keywords

Inverted flag▼ashape ratio▼aenergy harvesting▼ahydrodynamic force; 역방향 깃발▼a형상 계수▼a에너지 하베스팅▼a동유체력

URI
http://hdl.handle.net/10203/265880