A Study on the Near Wake of a Square Cylinder Using Particle Image Velocimetry (II)- Turbulence Characteristics -

- Journal title : Transactions of the Korean Society of Mechanical Engineers B
- Volume 25, Issue 10, 2001, pp.1417-1426
- Publisher : The Korean Society of Mechanical Engineers
- DOI : 10.22634/KSME-B.2001.25.10.1417

Title & Authors

A Study on the Near Wake of a Square Cylinder Using Particle Image Velocimetry (II)- Turbulence Characteristics -

Lee, Man-Bok; Kim, Gyeong-Cheon;

Lee, Man-Bok; Kim, Gyeong-Cheon;

Abstract

Turbulent flow characteristics in the near wake of a square cylinder have been studied experimentally by using a Digital PIV method. Experiments are performed at the Reynolds numbers of 1600 and 3900 based on the free-stream velocity and the square height. The ensemble averaged turbulence statistics are acquired from 2030 realizations of instantaneous fluctuating velocity field after the conventional Reynolds decomposition. The differences in turbulent intensity and Reynolds shear stress profiles fur both oases indicate that the effect of Reynolds number seems to be descernible mainly due to the occurrence of transition in the separated shear layer. Because of the periodic nature of vortex shedding process, transverse velocity fluctuations contribute dominantly , to turbulent kinetic energy distribution. A comparison with previous LDV data obtained at much higher Reynolds number shows a fairly good agreement each other. It turns out that the effect of Reynolds number diminishes as increasing Reynolds number, which is a well-known feature of a sharp-edged bluff body wake. The streamwise variation of turbulence intensities are compared with those from a circular cylinder along the centerline at the same Reynolds number. The overall magnitudes and the decay rates of turbulence intensities are quite similar, but some differences are noticeble especially in the transverse intensity variation.

Keywords

Square Cylinder;Near Wake;Vortex Shedding;Particle Image Velocimetry;Coherent Structure;Separated Shear Layers;Turbulence Characteristics;

Language

Korean

References

1.

Cantwell, B. and Coles, D., 1983, 'An Experimental Study of Entrainment and Transport in the Turbulent Near Wake of a Circular Cylinder,' J. Fluid Mech., Vol. 136, pp. 321-374

2.

부정숙, 윤순현, 이종춘, 강창수, 1985, '원주뒤의 2차원 후류 유동 특성,' 대한기계학회 논문집, 제 9권, 제 5호, pp. 555-563

3.

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

4.

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

5.

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

6.

Bosch, G. and Rodi, W., 1998, 'Simulation of Vortex Shedding Past a Square Cylinder with Different with bulence Models,' International journal for Numerical methods in fluids, Vol. 28, pp. 601-616

7.

Saha, A. K., muralidhar, K. and Biswas, G., 2000, 'Vortex Structures and Kinetic Energy Budget in Two-Dimensional Flow Past a Square Cylinder,' (An international journal)Computers & fluids, Vol. 29, No.6, pp. 669-694

8.

Sohankar, A., Dabidson, L. and Norberg C., 2000, 'Large Eddy Simulation of Flow Past a Square Cylinder: Comparison of Different Subgrid Scale Models,' Journal of Fluids Engineering, Vol. 122, pp. 39-47

9.

Robichaux, J. , Balachandar, S. and Vanka, S. P., 1999, 'Three-Dimensional Floquet instability of the Wake of Square Cylinder.,' Physics of fluids A, Fluid dynamics, Vol. 11, No. 3, pp. 560-578

10.

Bradshaw, P., 1968, 'An Instruction to Turbulence and Its Measurement,' Pergamon Press