Hostname: page-component-8448b6f56d-m8qmq Total loading time: 0 Render date: 2024-04-18T18:03:39.438Z Has data issue: false hasContentIssue false
  • English
  • Français

Vortex-induced streamwise oscillations of a square-section cylinder in a uniform stream

Published online by Cambridge University Press:  26 April 2006

E. D. Obasaju ,
R. Ermshaus  and
E. Naudascher
E. D. Obasaju
Affiliation:
Sonderforschungsbereich 210, ‘Strömungsmechanische Bemessungsgrundlagen für Bauwerke’, Universität Karlsruhe, West Germany Present address: BMT Fluid Mechanics Limited, Orlando House. I Waldegrave Road, Teddington, Middlesex TW11 8LZ, UK.
R. Ermshaus
Affiliation:
Sonderforschungsbereich 210, ‘Strömungsmechanische Bemessungsgrundlagen für Bauwerke’, Universität Karlsruhe, West Germany
E. Naudascher
Affiliation:
Sonderforschungsbereich 210, ‘Strömungsmechanische Bemessungsgrundlagen für Bauwerke’, Universität Karlsruhe, West Germany
Get access Rights & Permissions [Opens in a new window]

Abstract

The stream wise oscillation of a spring-mounted square-section cylinder set at angles of incidence, α, in the range from 0° to 45° is investigated in the reduced-velocity range 3 < U/ND < 13 and Reynolds-number range from 3.2 × 103 to 1.4. × 104. The mass-damping parameter used for the investigations is 1.6 and this gives vibration amplitude up to 0.12D. For small angles of incidence (i.e. α < 10°), vibration occurs mainly near U/ND = ½S, where S is the Strouhal number for the stationary cylinder. In the neighbourhood of α = 13.5°, which is where one of the separated shear layers is expected to reattach, vibration occurs near U/ND = 1/S. As α approaches 45° the amplitude observed near U/ND = 1/S diminishes and small-amplitude vibration appears near U/ND = ½S.

At α = 0°, vortices help to sustain oscillations by shedding when the cylinder is moving upstream. The mean drag of the oscillating cylinder drops and may reach less than half the stationary-cylinder value. When the amplitude of vibration is small, vortices of opposite sense of rotation are shed alternately and the familiar von Karman vortex street is formed. For moderately high values of amplitude, two vortex patterns fundamentally different from that of the stationary cylinder are observed. Intermittently, pairs of vortices are then shed symmetrically from both sides of the cylinder. When this occurs a pair of contra-rotating vortices forms every cycle of the vibration. When vortices of opposite sign are shed alternately, one vortex from each side of the cylinder forms every two vibration cycles. In this latter case, it appears that each vortex is elongated and split into two parts. Split vortices of opposite sign pair up and then form a vortex street.

Type
Research Article
Information
Journal of Fluid Mechanics , Volume 213 , April 1990 , pp. 171 - 189
Copyright
© 1990 Cambridge University Press

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Bearman, P. W. 1984 Vortex shedding from oscillating bluff bodies. Ann. Rev. Fluid Mech. 16, 195–222.Google Scholar
Bearman, P. W., Downie, M. J., Graham, J. M. R. & Obasaju, E. D. 1985 Forces on cylinders in viscous oscillatory flow at low Keulegan—Carpenter numbers. J. Fluid Mech. 104, 337–356.Google Scholar
Bearman, P. W. & Obasaju, E. D. 1982 An experimental study of pressure fluctuations on fixed and oscillating square-section cylinders. J. Fluid Mech. 119, 297–321.Google Scholar
Bearman, P. W. & Trueman, D. M. 1972 An investigation of the flow around rectangular cylinders. Aeronaut. Q. 23, 229–237.Google Scholar
Ermshaus, R., Knisely, C. & Naudascher, E. 1985 Flow visualisation in the wake of three-dimensional bodies undergoing self-sustained oscillations. In Optical Methods in Dynamics of Fluids and Solids (ed. M. Pichal). Springer.
Ermshaus, R., Naudascher, E. & Obasaju, E. D. 1986 Stromungserregte Schwingungen zylindrischer und axialsymmetrischer Körper in Strömungsrichtung. Bericht Nr. SFB 210/E/25. Universität Karlsruhe, W. Germany.
Freymuth, P., Bank, W. & Palmer, M. 1985 Further experimental evidence of vortex splitting. J. Fluid Mech. 152, 289–299.Google Scholar
Griffin, O. M. & Ramberg, S. E. 1976 Vortex shedding from a cylinder vibrating in line with an incident uniform flow. J. Fluid Mech. 75, 257–271.Google Scholar
King, R. 1974 Vortex excited structural oscillations of a circular cylinder in steady currents. Offshore Tech. Conf. Paper OTC 1948.Google Scholar
King, R. 1977 A review of vortex shedding research and its application. Ocean Engng 4, 141–171.Google Scholar
King, R., Prosser, M. J. & Johns, D. J. 1973 On vortex excitation of model piles in flowing water. J. Sound Vib. 29, 169–188.Google Scholar
Knisely, C. W. 1985 Strouhal numbers of rectangular cylinders at incidence. Rep. SFB 210/E/13, Universität Karlsruhe, W. Germany.
Kochin, N. E., Kibel, I. A. & Rozel, N. V. 1964 Theoretical Hydromechanics, pp. 218. Interscience.
Lee, B. E. 1975 The effect of turbulence on the surface pressure field of a square prism. J. Fluid Mech. 69, 263–282.Google Scholar
Nakamura, Y. & Nakashima, M. 1986 Vortex excitation of prisms with elongated rectangular, H and cross-sections. J. Fluid Mech. 163, 149–169.Google Scholar
Naudascher, E. 1987 Flow-induced streamwise vibration of structures. J. Fluids Structures 1, 265–298.Google Scholar
Obasaju, E. D. 1983 An investigation of the effects of incidence on the flow around a square section cylinder. Aeronaut. Q. 34, 243–259.Google Scholar
Ongoren, A. & Rockwell, D. 1988 Flow structure from an oscillating cylinder. Part 2. Mode competition in the near wake. J. Fluid Mech. 191, 225–245.Google Scholar
Schmitt, F. & Ruck, B. 1986 Laserlichtschnittverfahren zur qualitativen Strömungsanalyse. Laser Optoelektronik, Nr. 2. Stuttgart: AT-Fachverlag.
Steiner, T. R. & Perry, A. E. 1987 Large-scale vortex structures in turbulent wakes behind bluff bodies. Part 2. Far-wake structures. J. Fluid Mech. 174, 271–298.Google Scholar
Tanida, Y., Okajima, A. & Watanabe, Y. 1973 Stability of a circular cylinder oscillating in uniform flow or in a wake. J. Fluid Mech. 61, 769–784.Google Scholar
Williamson, C. H. K. & Roshko, A. 1988 Vortex formation in the wake of an oscillating cylinder. J. Fluids Structures 2, 355–381.Google Scholar