실린더 근접후류에서 위상학적 구조와 2차 와류의 상호 관계

DOI QR코드

DOI QR Code

성재용;유정열
Seong, Jae-Yong;Yu, Jeong-Yeol

  • 발행 : 2001.10.01

초록

Characteristics of secondary vortices is topologically investigated in the near-wake region of a circular cylinder, where the Taylor's hypothesis does nut hold. The three-dimensional flow fields in the wake-transition regime were measured by a time-resolved PIV for various planes of view. The convection velocities of the Karman and secondary vortices are evaluated from the trajectory of the vortex center. Then, saddle points are determined by applying the critical point theory. It is shown that the inclination angle of the secondary vortices agrees well with the previous experimental data. The flow fields in a moving frame of reference have several critical points and the mushroom-like structure appears in the streamline patterns of the secondary vortices. Since the distributions of fluctuating Reynolds stresses defined by triple decomposition are closely related with the existence of secondary vortices, the physical meaning of them is explained in conjunction with the vortex center and saddle point trajectories.

키워드

위상학적 구조;임계점;대류속도;섭동 레이놀즈 응력;고속 PIV

참고문헌

  1. Hayakawa, M. and Hussain, F., 1989, 'Three-Dimensionality of Organized Structures in a Plane Turbulent Wake,' J. Fluid Mech., Vol. 206, pp.375-404 https://doi.org/10.1017/S0022112089002338
  2. Wu, J., Sheridan, J. and Welsh, M. C., 1996, 'Velocity Perturbations Induced by the Longitudinal Vortices in a Cylinder Wake,' J. Fluids Engrg., Vol. 118, pp. 531-536
  3. Roshko, A., 1954, 'On the Development of Turbulent Wakes from Vortex Streets,' NACA Rep. 1191
  4. Fey, D., K nig, M. and Eckelmann, H., 1998, 'A New Strouhal-Reyno1ds-Number Relationship for the Circular Cylinder in the Range $47 < Re < 2x10^5$,' Phys. Fluids, Vol. 10, No.7, pp. 1547-1549 https://doi.org/10.1063/1.869675
  5. Williamson, C. H. K., 1996, 'Vortex Dynamics in the Cylinder Wake,' Ann. Rev. Fluid Mech., Vol. 28, pp 477-539 https://doi.org/10.1146/annurev.fl.28.010196.002401
  6. Perry, A. E. and Tan, D. K. M., 1984, 'Simple Three-Dimensional Vortex Motions in Coflowing Jets and Wakes,' J. Fluid Mech., Vol. 141, pp. 197-231 https://doi.org/10.1017/S002211208400080X
  7. Zhou, Y. and Antonia, R. A., 1992, 'Convection Velocity Measurements in a Cylinder Wake,' Exp. Fluids, Vol. 13, pp. 63-70
  8. Hussain, A. K. M. F. and Reynolds, W. C., 1970, 'The Mechanics of an Organized Wave in Turbulent Shear Flow,' J. Fluid Mech., Vol. 41, pp. 241-258 https://doi.org/10.1017/S0022112070000605
  9. Perny, A. E. and Steiner, T. R., 1987, 'Large-Scale Vortex Structures in Turbulent Wakes Behind Bluff Bodies. Part 1. Vortex Formation Processes,' J. Fluid Mech., Vol. 174, pp. 233-270 https://doi.org/10.1017/S0022112087000119
  10. Wu, J., Sheridan, J., Welsh, M. C. and Hourigan, K., 1996, 'Three-dimensional Vortex Structures in a Cylinder Wake,' J. Fluid Mech., Vol. 312, pp. 201-222 https://doi.org/10.1017/S0022112096001978
  11. Perry, A. E., Lim, T. T. and Chong, M. S., 1980, 'The Instantaneous Velocity Fields of Coherent Structures in Coflowing Jets and Wakes,' J. Fluid Mech., Vol. 101, pp. 243-256 https://doi.org/10.1017/S0022112080001644
  12. Zhou, Y. and Antonia, R. A., 1994, 'Critical Points in a Turbulent Near Wake,' J. Fluid Mech., Vol. 275, pp 59-81 https://doi.org/10.1017/S0022112094002284
  13. 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 https://doi.org/10.1017/S0022112083002189
  14. Chong, M. S., Perry, A. E. and Cantwell, B. J., 1990, 'A General Classification of Three-Dimensional Flow Fields,' Phys. Fluids A, Vol. 2, No.5, pp. 765-777 https://doi.org/10.1063/1.857730
  15. Hussain, A. K. M. F. and Hayakawa, M., 1987, 'Eduction of Large-Scale Organized Structures in a Turbulent Plane Wake,' J. Fluid Mech., Vol. 180, pp. 193-229 https://doi.org/10.1017/S0022112087001782
  16. Brede, M., Eckelmann, H. and Rockwell, D., 1996, 'On Secondary Vortices in the Cylinder Wake,' Phys. Fluids, Vol. 8, No.8, pp. 2117-2124 https://doi.org/10.1063/1.868986
  17. 성재용, 유정열, 2000, 'Cinematic PIV 데이터의 3 차원 위상평균 기법을 이용한 실린더 후류의 2차 와류 측정,' 대한기계학회논문집 B, 제 24권, 제 11호, pp. 1540-1548
  18. Perry, A. E. and Chong, M. S., 1987, 'A Description of Eddying Motions and Flow Patterns Using Critical-Point Concepts,' Ann. Rev. Fluid Mech., Vol. 19, pp. 125-155 https://doi.org/10.1146/annurev.fl.19.010187.001013
  19. Mansy, H., Yang, P. M. and Williams, D. R., 1994, 'Quantitative Measurements of Three-Dimensional Structures in the Wake of a Circular Cylinder,' J. Fluid Mech., Vol. 270,pp. 277-296 https://doi.org/10.1017/S0022112094004271
  20. Lin, J.-C., Vorobieff, P. and Rockwell, D., 1996, 'Space-Time Imaging of a Turbulent Near-Wake by High-Image-Density Particle Image Cinematography,' Phys. Fluids, Vol. 8, No.2, pp. 555-564 https://doi.org/10.1063/1.868808
  21. Gerrard, J. H., 1978, 'The Wakes of Cylindrical Bluff Bodies at Low Reynolds Number,' Philosophical Transactions of the Royal Society of London, Series A, Vol. 288, pp. 351-382 https://doi.org/10.1098/rsta.1978.0020
  22. Wei, T. and Smith, C. R., 1986, 'Secondary vortices in the Wake of Circular Cylinders,' J. Fluid Mech., Vol. 169, pp. 513-533 https://doi.org/10.1017/S0022112086000733
  23. Hussain, A. K. M. F., 1986, 'Coherent Structures and Turbulence,' J. Fluid Mech., Vol. 173, pp. 303-356 https://doi.org/10.1017/S0022112086001192
  24. Williamson, C. H. K., 1996, 'Three-Dimensional Wake Transition,' J. Fluid Mech., Vol. 328, pp. 345-407 https://doi.org/10.1017/S0022112096008750