Study on Vibration of Submerged Spheres Caused by Surface Waves

Shi-igai, Hiroyoshi; Kono, Tsugio

doi:10.1080/05785634.1969.11924088

Cited by 15 publications

(8 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Most previous work regarding tethered bodies has focused on the free surface interaction with tethered buoys (Harlemann and Shapiro, 1961;Shi-Igai and Kono, 1969;Ogihara, 1988 oscillate due to the combined effect of a uniform (or sheared) free stream and free surface wave effects. This combination, incorporating the interaction of a free surface, has made interpretation of results complex and conclusions difficult to draw.…”

Section: Introductionmentioning

confidence: 99%

Flow-induced vibrations of a tethered circular cylinder

Ryan

Pregnalato

Thompson

et al. 2004

Journal of Fluids and Structures

View full text Add to dashboard Cite

Section: Introductionmentioning

confidence: 99%

Flow-induced vibrations of a tethered circular cylinder

Ryan

Pregnalato

Thompson

et al. 2004

Journal of Fluids and Structures

View full text Add to dashboard Cite

“…Gross errors in predictions of mean response of a tethered structure will ensue unless one takes account of their tendency to vibrate. Other studies in the literature are concerned with the action of surface waves on tethered buoyant structures, and they employ empirically-determined drag and inertia coe$cients to predict sphere dynamics (Harleman & Shapiro 1961;Shi-Igai & Kono 1969;Ogihara 1980).…”

Section: Introductionmentioning

confidence: 99%

Multiple Modes of Vortex-Induced Vibration of a Sphere

Jauvtis

Govardhan

Williamson

2001

Journal of Fluids and Structures

View full text Add to dashboard Cite

“…The range of Reynolds numbers for the present investigation is from Re = 2000 to Re = 12 000. Although not directly relevant to the present problem, it should also be mentioned that there have been some previous investigations of the dynamics of a tethered sphere in surface waves (Harleman & Shapiro 1961;Shi-Igai & Kono 1969;Ogihara 1980;Vethamony, Chandramohan & Sastry 1992;Carpenter, Leonard & Yim 1995).…”

Section: Introduction and Preliminary Workmentioning

confidence: 99%

Vortex-induced vibrations of a sphere

2005

View full text Add to dashboard Cite

There are many studies on the vortex-induced vibrations of a cylindrical body, but almost none concerned with such vibrations for a sphere, despite the fact that tethered bodies are a common configuration. In this paper, we study the dynamics of an elastically mounted or tethered sphere in a steady flow, employing displacement, force and vorticity measurements. Within a particular range of flow speeds, where the oscillation frequency ($f$) is of the order of the static-body vortex shedding frequency ($f_{vo})$, there exist two modes of periodic large-amplitude oscillation, defined as modes I and II, separated by a transition regime exhibiting non-periodic vibration. The dominant wake structure for both modes is a chain of streamwise vortex loops on alternating sides of the wake. Further downstream, the heads of the vortex loops pinch off to form a sequence of vortex rings. We employ an analogy with the lift on an aircraft that is associated with its trailing vortex pair (of strength $\Gamma^*$ and spacing $b^*$), and thereby compute the rate of change of impulse for the streamwise vortex pair, yielding the vortex force coefficient ($\cvortex$): \[ \cvortex = \frac{8}{\pi} {U^*_{v}}b^*( - \Gamma^*). \] This calculation yields predicted forces in reasonable agreement with direct measurements on the sphere. This is significant because it indicates that the principal vorticity dynamics giving rise to vortex-induced vibration for a sphere are the motions of these streamwise vortex pairs. The Griffin plot, showing peak amplitudes as a function of the mass–damping ($m^*\zeta$), exhibits a good collapse of data, indicating a maximum response of around 0.9 diameters. Following recent studies of cylinder vortex-induced vibration, we deduce the existence of a critical mass ratio, $m^*_{crit} {\approx} 0.6$, below which large-amplitude vibrations are predicted to persist to infinite normalized velocities. An unexpected large-amplitude and highly periodic mode (mode III) is found at distinctly higher flow velocities where the frequency of vibration ($f$) is far below the frequency of vortex shedding for a static body. We find that the low-frequency streamwise vortex pairs are able to impart lift (or transverse force) to the body, yielding a positive energy transfer per cycle.

show abstract

Study on Vibration of Submerged Spheres Caused by Surface Waves

Cited by 15 publications

References 0 publications

Flow-induced vibrations of a tethered circular cylinder

Flow-induced vibrations of a tethered circular cylinder

Multiple Modes of Vortex-Induced Vibration of a Sphere

Vortex-induced vibrations of a sphere

Contact Info

Product

Resources

About