Excitation, inertia, and drag forces on a cylinder vibrating transversely to a steady flow

Kaiktsis, L; Triantafyllou, GS; Ozbas, M

dc.contributor.author	Kaiktsis, L	en
dc.contributor.author	Triantafyllou, GS	en
dc.contributor.author	Ozbas, M	en
dc.date.accessioned	2014-03-01T01:26:19Z
dc.date.available	2014-03-01T01:26:19Z
dc.date.issued	2007	en
dc.identifier.issn	0889-9746	en
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/18012
dc.subject	Oscillating cylinder	en
dc.subject	Spectral element method	en
dc.subject	Vortex-induced vibrations	en
dc.subject.classification	Engineering, Mechanical	en
dc.subject.classification	Mechanics	en
dc.subject.other	Drag	en
dc.subject.other	Flow visualization	en
dc.subject.other	Hydrodynamics	en
dc.subject.other	Natural frequencies	en
dc.subject.other	Navier Stokes equations	en
dc.subject.other	Oscillations	en
dc.subject.other	Reynolds number	en
dc.subject.other	Steady flow	en
dc.subject.other	Wakes	en
dc.subject.other	Lift force	en
dc.subject.other	Resonant forcing	en
dc.subject.other	Spectral element method	en
dc.subject.other	Vortex-induced vibrations	en
dc.subject.other	Cylinders (shapes)	en
dc.subject.other	Cylinders (shapes)	en
dc.subject.other	Drag	en
dc.subject.other	Flow visualization	en
dc.subject.other	Hydrodynamics	en
dc.subject.other	Natural frequencies	en
dc.subject.other	Navier Stokes equations	en
dc.subject.other	Oscillations	en
dc.subject.other	Reynolds number	en
dc.subject.other	Steady flow	en
dc.subject.other	Wakes	en
dc.title	Excitation, inertia, and drag forces on a cylinder vibrating transversely to a steady flow	en
heal.type	journalArticle	en
heal.identifier.primary	10.1016/j.jfluidstructs.2006.08.006	en
heal.identifier.secondary	http://dx.doi.org/10.1016/j.jfluidstructs.2006.08.006	en
heal.language	English	en
heal.publicationDate	2007	en
heal.abstract	We present a computational study of the forces on a cylinder oscillating harmonically in the direction perpendicular to a uniform flow. The two-dimensional Navier-Stokes equations are solved on a coordinate system fixed on the cylinder. The Reynolds number is equal to 400. Several oscillation frequencies are considered: (a) resonant forcing, (b) forcing at frequency below the natural frequency of the wake, and (c) forcing at frequency above the natural frequency of the wake. Once the flow has reached a statistical steady state, the lift and drag forces on the cylinder are computed. The lift force in particular is decomposed into one component that is in phase with the velocity (excitation force), and one component that is 180{ring operator} out of phase with the acceleration (inertia or added mass force). The variation of the forces as a function of the amplitude-over-diameter-ratio is studied in detail. It is found that the scaling of the so-called inertia component of the force with the acceleration of the cylinder can lead to serious problems at small amplitudes of oscillation, and that it is overall preferable to scale both components of the force with the dynamic pressure of the fluid. Through extensive flow visualization, it is shown that changes in the state of the flow are related to the abrupt changes of the forces with the amplitude-over-diameter-ratio. Moreover, qualitative differences are found between the results for the below resonance and the resonant or above resonance forcing. The former are characterized by smooth variation of the hydrodynamic force coefficients and spatially ordered vortex streets. The latter are characterized by continuous and sharp, even jump-like, changes of the forces, and a variety of vortex patterns in the wake, resulting for some combinations of frequency and amplitude of oscillation to spatially disordered vortex streets. © 2006 Elsevier Ltd. All rights reserved.	en
heal.publisher	ACADEMIC PRESS LTD ELSEVIER SCIENCE LTD	en
heal.journalName	Journal of Fluids and Structures	en
dc.identifier.doi	10.1016/j.jfluidstructs.2006.08.006	en
dc.identifier.isi	ISI:000243749200001	en
dc.identifier.volume	23	en
dc.identifier.issue	1	en
dc.identifier.spage	1	en
dc.identifier.epage	21	en