A Study on the Near Wake of a Square Cylinder Using Particle Image Velocimetry ( I )- Mean Flow Field -

Title & Authors
A Study on the Near Wake of a Square Cylinder Using Particle Image Velocimetry ( I )- Mean Flow Field -
Lee, Man-Bok; Kim, Gyeong-Cheon;

Abstract
Mean flow fields in the near wake of a square cylinder have been studied experimentally using a Particle Image Velocimetry (PIV). Ensemble-averaged velocity fields are successfully measured fur the square cylinder wake including the reverse flow region which arises many difficulties in accurate measurement by using conventional techniques, Experiments are performed at two free stream velocities of U$\small{\_}$$\small{\infty}$/ = 1.27m/s and 3.03m/s. The corresponding Reynolds numbers based on the free-stream velocity and cylinder diameter are 1600 and 3900, respectively. The intensity of free-stream turbulence is less than 1%, the blockage ratio (D/H) is 6.6% and the aspect ratio (W/D) is 40. The effect of Reynolds number on the near wake of a square cylinder has been investigated by the global mean velocity and instantaneous velocity fields. The most striking feature is that the length of the recirculating region increases with increasing Reynolds number, which turns out totally reverse trend compared with those observed in the circular cylinder wake at the same range of Reynolds number. Fer the case of higher Reynolds number, the mean velocity data agree well with those of relevant existing data obtained at much higher Reynolds numbers, which reflects the general aspect of sharp-edged bluff body wake.
Keywords
Square Cylinder;Near Wake;Mean Flow Field;Particle Image Velocimetry;Recirculating Region;
Language
Korean
Cited by
1.
An Experimental Study on Swirling Flow behind a Round Cylinder in the Horizontal Circular Tube,Chang Tae-Hyun;Lee Hae Soo;

Journal of Mechanical Science and Technology, 2005. vol.19. 12, pp.2270-2280
2.
파랑상태에 있는 실린더 구조물 주위의 PIV유동 해석,조효제;도덕희;이언주;

한국가시화정보학회지, 2011. vol.9. 3, pp.51-58
3.
PIV기법을 이용한 정사각 실린더의 후류에 관한 실험적 연구,이종붕;장태현;

한국마린엔지니어링학회지, 2004. vol.28. 1, pp.124-135
References
1.
Roshko, A., 1961, 'Experiment on the Flow Past a Circular Cylinder at very High Reynolds Numbers,' J. Fluid Mech., Vol. 10, pp. 345-356

2.
Nakaguchi, H., 1968, 'An Experimental Study of Aerodynamic Drag of Rectangular Cylinder,' J. Japan Soc. Aero. Space Sci. Vol. 16, pp. 1-5

3.
Okajima, A., 1982, 'Strouhal Numbers of Rectangular Cylinders,' J. Fluid Mech., Vol. 123, pp. 379-398

4.
Sakamoto, H. and Arie, M., 1983, 'Vortex Shedding from a Rectangular Prism and a Circular Cylinder Placed Vertically in a Turbulent Boundary Layer,' J. Fluid Mech., Vol. 126, pp. 147-165

5.
Lyn, D. A., Einav, S., Rodi, W. and Park, J. H., 1995, 'A Laser-Doppler Velocimetry Study of the Ensemble-Averaged Characteristics of the turbulent Near Wake of a Square Cylinder,' J. Fluid Mech., Vol. 304, pp. 285-319

6.
Saha, A. K., Muralidhar, K., Biswas, G., 'Experimental Study of Flow Past a Square Cylinder at High Reynolds Numbers,' Exps. Fluids., Vol. 29, pp. 553-563

7.
Williamson, C. H. K., 1996, 'Vortex Dynamics in the Cylinder Wake,' Annu. Rev. Fluid Mech., Vol. 28, pp. 477-539

8.
Yoon, S. Y., 1999, 'PIV Measurements in the Turbulent Near Wake of a Circular Cylinder,' M.S. Thesis, Mechanical Engineering, Pusan National University

9.
윤상열, 김상기, 김경천, 1999, '원주의 근접후류에 대한 레이놀즈수 영향 : PIV측정,' 대한기계학회 추계학술대회논문집 B, pp. 793-798

10.
Lourenco, L. and Shih, C. 1993, 'Characteristics of the Plane Turbulent Near Wake of a Circular Cylinder: A Particle Image Velocimetry Study,' Not published

11.
West, G. S. and Apelt, C. J,, 1982, 'The Effects of Tunnel Blockage and Aspect Ratio on the. Mean Flow Past a Circular Cylinder with Reynolds Numbers between $10^4$ and $10^5$,' J. Fluid Mech., Vol. 114, pp. 361-377

12.
Durao, D. F. G., Heitor, M. V. and Pereira, J. C. F., 1988, 'Measurements of Turbulent an Periodic Flows around a Square Cross-Section Cylinder,' Exps. Fluids., Vol. 6, pp. 298-304

13.
Hassan, M. A. Z., 1989, 'The Near Wake Structure of a Square Cylinder,' Int. J. Heat and Fluid Flow, Vol. 10, No.4, pp. 339-348

14.
Kravchenko, G. and Moin, P., 2000, 'Numerical Studies of Flow over a Circular Cylinder at $Re_D=3900$,' Physics of Fluids, Vol. 12, No.2, pp. 403-417