Numerical simulation of Reynolds number effects on velocity shear flow around a circular cylinder |
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| Authors: | Shuyang Cao Shigehira Ozono Yukio Tamura Yaojun Ge Hironori Kikugawa |
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| Affiliation: | 1. State Key Lab for Disaster Reduction in Civil Engineering, Tongji University, Siping Road 1239, Shanghai 200092, China;2. Faculty of Engineering, Miyazaki University, Miyazaki 889-2192, Japan;3. Tokyo Polytechnic University, 1583 Iiyama, Atsugi, Kanagawa 243-0297, Japan;4. Department of Mechanical Engineering, Oita National College of Technology, Oita 870-0152, Japan;1. School of Civil and Environmental Engineering, Nanyang Technological University, Singapore;2. Centre for Offshore Research and Engineering, Department of Civil and Environmental Engineering, National University of Singapore, 1 Engineering Drive 2, Singapore 117576, Singapore;1. Institute for Turbulence-Noise-Vibration Interaction and Control, Shenzhen Graduate School, Harbin Institute of Technology, Shenzhen, China;2. Key Lab of Advanced Manufacturing and Technology, Shenzhen Graduate School, Harbin Institute of Technology, Shenzhen, China;1. School of Civil Engineering, Key Laboratory of New Technology for Construction of Cities in Mountain Area, Chongqing University, Chongqing, 400045, PR China;2. Department of Civil Engineering, School of Engineering, The University of Tokyo, 113-8656, Japan |
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| Abstract: | Three-dimensional Direct Numerical Simulation (DNS) and Large Eddy Simulation (LES) are performed to investigate the shear effects on flow around a circular cylinder at Reynolds numbers of Re=60–1000. The shear parameter, β, which is based on the velocity gradient, cylinder diameter and upstream mean velocity at the center plane of the cylinder, varies from 0 to 0.30. Variations of Strouhal number, drag and lift coefficients, and unsteady wake structures with shear parameter are studied, along with their dependence on Reynolds number. The presented simulation provides detailed information for the flow field around a circular cylinder in shear flow. This study shows that the Strouhal number exhibits no significant variation with shear parameter. The stagnation point moves to the high-velocity side almost linearly with shear parameter, and this result mainly influences the aerodynamic forces acting on a circular cylinder in shear flow. Both the Reynolds number and shear parameter influence the movement of the stagnation point and separation point. Mode A wake instability is suppressed into parallel vortex shedding mode at a certain shear parameter. The lift force increases with increasing shear parameter and acts from the high-velocity side to the low-velocity side. In addition, a simple method to estimate the lift force coefficient in shear flow is provided. |
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