Analyzing the fluctuating pressures acting on a circular cylinder using stochastic decomposition |
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| Institution: | 1. School of Civil Engineering, Harbin Institute of Technology, Heilongjiang, Harbin 150090, China;2. Key Lab of Structures Dynamic Behavior and Control, Harbin Institute of Technology, Ministry of Education, Heilongjiang, Harbin 150090, China;3. Tokyo Polytechnic University, 1583 Iiyama, Atsugi, Kanagawa 243-0297, Japan;1. Centro de Investigación de Métodos Computacionales (CIMEC), UNL, CONICET, Predio “Dr. Alberto Cassano”, Colectora Ruta Nacional 168 s/n, 3000, Santa Fe, Argentina;2. Facultad de Ingeniería y Ciencias Hídricas - Universidad Nacional del Litoral, Ciudad Universitaria, Paraje “El Pozo”, Santa Fe, Argentina;1. University of Florida, Gainesville, FL, USA;2. Tohoku University, Sendai, Japan;1. Department of Chemical Engineering, National Institute of Technology Srinagar, Hazratbal 190 006, India;2. Department of Chemical Engineering, Indian Institute of Technology Roorkee, Roorkee 247 667, India;3. Department of Mechanical Engineering, National Institute of Technology Srinagar, Hazratbal 190 006, India |
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| Abstract: | Fluctuating wind pressures acting on bluff bodies are influenced by approaching turbulence and signature (body-induced) turbulence. For a circular cylinder, the signature turbulence is closely related to the formation of Karman vortex shedding. In this paper, proper orthogonal decomposition (POD) and spectral proper transformation techniques (SPT) are applied to the pressure fluctuations acting on a circular cylinder. The physical relationships between the decomposed modes and vortex shedding are discussed to identify the dominant aerodynamic behavior (lift or drag) and to evaluate its contribution to overall behavior. The effect of Reynolds number (Re) is also addressed. It is found that the application of POD and SPT can separate the along-wind and across-wind effects on the cylinder model in both subcritical and supercritical regimes. In contrast to POD, the SPT mode is formulated in the frequency domain, and the dynamic coherent structures can be defined in terms of amplitude and phase angle, which allows detection of the advection features of vortex shedding. In addition, it is observed that the energy contribution of the shedding induced lift force increases with Re and gradually becomes a dominant aerodynamic force at Reynolds numbers in the supercritical regime. |
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| Keywords: | Circular cylinder Coherent structure POD Reynolds number Spectral proper transformation |
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