Flow structures around an equilateral triangle arrangement of three spheres |
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| Institution: | 1. Chair of Fluid Process Engineering, University of Paderborn, Pohlweg 55, 33098 Paderborn, Germany;2. Gubkin Russian State University of Oil and Gas, Moscow, Russian Federation;1. Department of Applied Mathematics, University of Science and Technology, Beijing 100083, China;2. Department of Mechanical Engineering, University of Science and Technology, Beijing 100083, China;1. Key Laboratory of Enhanced Heat Transfer and Energy Conservation of Education Ministry, School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou 510640, China;2. State Key Laboratory of Subtropical Building Science, South China University of Technology, Guangzhou 510640, China;1. State Key Laboratory of Hydraulic Engineering Simulation and Safety, Tianjin University, Tianjin 300072, China;2. Department of Civil, Environmental and Geomatic Engineering, University College London, London WC1E 6BT, UK;1. Key Laboratory of Mechanics on Disaster and Environment in Western China (Lanzhou University), The Ministry of Education of China, PR China;2. School of Civil Engineering and Mechanics, Lanzhou University, Lanzhou 730000, PR China;1. Research Institute for Applied Mechanics, Kyushu University, 6-1, Kasuga-Kohen, Kasuga, Fukuoka 816-8580, Japan;2. UTokyo Ocean Alliance, The University of Tokyo, Tokyo, Japan;3. Division of Earth and Planetary Sciences, Graduate School of Science, Kyoto University, Kyoto, Japan |
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| Abstract: | This paper represents the results of an experimental study on the flow structure around a single sphere and three spheres in an equilateral-triangular arrangement. Flow field measurements were performed using a Particle Image Velocimetry (PIV) technique and dye visualization in an open water channel for a Reynolds number of Re = 5 × 103 based on the sphere diameter. The distributions and flow features at the critical locations of the contours of the velocity fluctuations, the patterns of sectional streamlines, the vorticity contours, the turbulent kinetic energy, the Reynolds stress correlations and shedding frequency are discussed. The gap ratios (G/D) of the three spheres were varied in the range of 1.0 ? G/D ? 2.5 where G was the distance between the sphere centers, and D was the sphere diameter which was taken as 30 mm. Due to the interference of the shedding shear layers and the wakes, more complex features of the flow patterns can be found in the wake region of the two downstream spheres behind the leading sphere. For G/D = 1.25, a jet-like flow around the leading sphere through the gap between the two downstream spheres occurred, which significantly enhanced the wake region. It was observed that a continuous flow development involving shearing phenomena and the interactions of shedding vortices caused a high rate of fluctuations over the whole flow field although most of the time-averaged flow patterns were almost symmetric about the two downstream spheres. |
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