1Department of Mechanical Engineering and Materials Science, Kumamoto University, 2-39-1 Kurokami, Kumamoto, 860–8555, Japan.
2Department of Mechanical Engineering and Applied Mechanics, University of Michigan, Ann Arbor, Michigan, 48109, USA.
3Department of Civil Engineering, Fukuyama University, Fukuyama, Hiroshima, 729-08, Japan.
NomenclatureB
computational domain in the x direction, m
Huliquid level in the upper tank, m
Llength of diamond-shaped island, m
nfrequency, 1/sec.
Ppressure, Pa
ReReynolds number, umδ/ν
StStrouhal number, Eq. (4), nδ/um
ttime, second
U, V,velocity components in streamwise and transverse directions, respectively, m/s
umaxial mean velocity of the main flow, m/s
x, ycoordinate, m
ΔX, ΔYmesh size, m
Wcomputational domain in the y direction, m
δwidth of diamond-shaped island, m
θangle of diamond-shaped island
ρdensity, kg/m3
νmolecular viscosity, m2/s
Two-dimensional flows over a single diamond-shaped cylinder in the free stream are experimentally and theoretically investigated. Consideration is given to the effects of the Reynolds number, Re, and the upstream angle of the diamond shape, θ, on flow phenomena. The study discloses that (i) the generation of von Karman vortex streets behind the diamond-shaped cylinder is intensified with an increase in the Reynolds number, (ii) the flow pattern in the wake region of the diamond-shaped island is affected by θ, and (iii) the relationship among the Strouhal number, St, Re and θ is determined and compared with the existing St-Re relationship for flow over a circular cylinder.
Diamond-shaped cylinder, numerical simulation, Strouhal number, Reynolds number, vortex motion, flow visualization
