On the development of lift and drag in a rotating and translating cylinder |
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Affiliation: | 1. Universidad de Málaga, Andalucía Tech, E. T. S. Ingeniería Industrial, Dr Ortiz Ramos s/n, 29071 Málaga, Spain;2. Universidad de Córdoba, Esc. Pol. Superior, Área de Ingeniería Mecánica, Campus de Rabanales, 14071 Córdoba, Spain;1. Faculty of Civil Engineering, K.N. Toosi University of Technology, Tehran, Iran;2. Department of Mechanical Engineering, Sharif University of Technology, Tehran, Iran;1. Área de Mecánica de Fluidos, Departamento de Ingeniería Mecánica y Minera, Universidad de Jaén, Campus de las Lagunillas, 23071 Jaén, Spain;2. Área de Ingeniería Mecánica, Departamento de Mecánica, Universidad de Córdoba, Campus de Rabanales, 14071 Córdoba, Spain;1. Faculty of Aeronautics and Astronautics, Department of Aerospace Engineering, Adana Science and Technology University, Adana, 01250, Turkey;2. Faculty of Ceyhan Engineering, Department of Mechanical Engineering, Cukurova University, Adana, Turkey;3. Faculty of Engineering, Department of Mechanical Engineering, Cukurova University, Adana, 01330, Turkey;4. School of Engineering, Department of Mechanical Engineering, Rice University, Houston, TX, 77005, USA |
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Abstract: | The two-dimensional flow around a rotating cylinder is investigated numerically using a vorticity forces formulation with the aim of analyzing quantitatively the flow structures, and their evolutions, that contribute to the lift and drag forces on the cylinder. The Reynolds number considered, based on the cylinder diameter and steady free stream speed, is Re=200, while the non-dimensional rotation rate (ratio of the surface speed and free stream speed) selected was α=1 and 3. For α=1 the wake behind the cylinder for the fully developed flow is oscillatory due to vortex shedding, and so are the lift and drag forces. For α=3 the fully developed flow is steady with constant (high) lift and (low) drag. Each of these cases is considered in two different transient problems, one with angular acceleration of the cylinder and constant speed, and the other one with translating acceleration of the cylinder and constant rotation. We characterize quantitatively the contributions of individual fluid elements (vortices) to aerodynamic forces, explaining and quantifying the mechanisms by which the lift is generated in each case. In particular, for high rotation (when α=3), we explain the relation between the mechanisms of vortex shedding suppression and those by which the lift is enhanced and the drag is almost suppressed when the fully developed flow is reached. |
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Keywords: | Vortex dynamics Rotating cylinder Lift and drag |
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