Korean Journal of Air-Conditioning and Refrigeration Engineering (설비공학논문집)

The Society of Air-Conditioning and Refrigerating Engineers of Korea (대한설비공학회)
권호 표지

Numerical Study of Flow Around an Oscillating Sphere

진동하는 구 주위의 유동에 관한 수치적 연구

  • Lee, Jin-Woog (School of Mechanical Engineering, Pusan National University) ;
  • Lee, Dae-Sung (School of Mechanical Engineering, Pusan National University) ;
  • Ha, Man-Yeong (School of Mechanical Engineering, Pusan National University) ;
  • Yoon, Hyun-Sik (Advanced Ship Engineering Research Center, Pusan National University)
  • 이진욱 (부산대학교 기계공학부) ;
  • 이대성 (부산대학교 기계공학부) ;
  • 하만영 (부산대학교 기계공학부) ;
  • 윤현식 (부산대학교 첨단조선공학연구센터)
  • Received : 2010.06.17
  • Published : 2010.11.10
Download PDF
⟨ Previous Next ⟩

Abstract

The incompressible viscous flow past a sphere under forced oscillation is numerically investigated at a Reynolds number of 300. The immersed boundary method is used to handle the sphere oscillating vertically to the streamwise direction. There are two important variables to characterize the oscillating state of a sphere. One is an oscillating amplitude normalized by the sphere diameter is set as a fixed number of 0.2. Another is the frequency ratio which is defined by $f_e/f_o$, where fe and fo are the excited frequency and the natural frequency of vortex shedding for the stationary sphere. In this study, three different frequency ratios of 0.8, 1.0 and 1.2 are considered. The results show a periodic flow with hairpin vortices shedding from upper and lower positions as well as vortical legs obliquely extended by oscillating motion of sphere. The enveloping vortical structure experience rupture twice in one period of oscillation. As the frequency of oscillation is increased, the vortical legs are getting shorter and eventually the hairpin vortices are much closer to the adjacent one.

Keywords

References

  1. Mittal, R., 1999, Planar symmetry in the unsteady wake of a sphere, AIAA J., Vol. 37, pp. 388-390. https://doi.org/10.2514/2.722
  2. Fornberg, B., 1988, Steady vicous flow past a sphere at high Reynolds numbers, J. Fluid Mech., Vol. 190, pp. 471-489. https://doi.org/10.1017/S0022112088001417
  3. Johnson, T. A. and Patel, V. C., 1999, Flow past a sphere up to a Reynolds number of 300, J. Fluid Mech., Vol. 378, pp. 19-70. https://doi.org/10.1017/S0022112098003206
  4. Tomboulides, A. G. and Orszag, S. A., 2000, Numerical investigation of transitional and weak turbulent flow past a sphere, J. Fluid Mech., Vol. 416, pp. 45-73. https://doi.org/10.1017/S0022112000008880
  5. Bagchi, P. and Balachandar, S., 2002, Steady plannar straining flow past a rigid sphere at moderate Reynolds number, J. Fluid Mech., Vol. 466, pp. 365-407.
  6. Kim, D. J. and Choi, H. C., 2002, Laminar flow past a sphere rotating in the stream wise direction, J. Fluid Mech., Vol. 461, pp. 365-386.
  7. Niazmand, H. and Renksizbulut, M., 2004, Heat transfer from a rotating sphere interacting with a vortex, Int. J. Heat Mass Transfer, Vol. 47, pp. 2269-2281. https://doi.org/10.1016/j.ijheatmasstransfer.2003.11.021
  8. Govardhan, R. N. and Williamson, C. H. K., 1997, Vortex-induced motions of a tethered sphere, J. Wind Eng. and Industrial Aerodynamics, Vol. 69-71, pp. 375-385. https://doi.org/10.1016/S0167-6105(97)00170-0
  9. Govardhan, R. N. and Williamson, C. H. K., 2005, Vortex-induced vibrations of sphere, J. Fluid Mech., Vol. 531, pp. 11-47. https://doi.org/10.1017/S0022112005003757
  10. Kim, D. J., 2001, Numerical study on dynamics and control of flow over a sphere up to Re = $10^{4}$, Ph. D. Thesis, Seoul National University.
  11. Johnson, T. A. and Patel, V. C., 1999, Flow past a sphere up to a Reynolds number of 300, J. Fluid Mech., Vol 378, pp. 19-70. https://doi.org/10.1017/S0022112098003206
  12. Jeong, J. and Hussain, F., 1995, On the identification of a vortex, J. Fluid Mech., Vol. 285, pp. 69-94. https://doi.org/10.1017/S0022112095000462
  13. Kim, D. J. and Choi, H. C., 2001, Immersed boundary method for flow around an arbitrarily moving body, J. Comp. Phys., Vol. 212, pp. 662-680.
  14. Meneghini, J. R. and Bearman, P. W., 1995, Numerical simulation of high amplitude oscillatory flow about a circular cylinder, J. Fluids Struct., Vol. 9, pp. 435-455. https://doi.org/10.1006/jfls.1995.1025
  15. Bearman, P. W., 1984, Vortex shedding from oscillating bluff bodies, Ann. Rev. Fluid Mech., Vol. 16, pp. 195-222. https://doi.org/10.1146/annurev.fl.16.010184.001211