doi:10.1016/j.jfluidstructs.2007.08.010
Copyright © 2008 Elsevier Ltd All rights reserved.
Frequency effects on lift and drag for flow past an oscillating cylinder
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Z.C. Zheng
, a, 
and N. Zhanga
aDepartment of Mechanical and Nuclear Engineering, Kansas State University, Manhattan, Kansas 66506, USA
Received 20 April 2007;
accepted 22 August 2007.
Available online 12 February 2008.
Abstract
A transversely oscillating cylinder in a uniform flow is modeled to investigate frequency effects of flow-induced wake on lift and drag of the cylinder. Specifically, verified unsteady fluid dynamic simulations using an immersed-boundary method in a fixed Cartesian grid predict the flow structure around the cylinder and reveal how the integration of surface pressure and shear distributions provides lift and drag on the oscillating cylinder. In this study, frequency ranges to be considered are both near and away from the natural frequency of wake vortex shedding. Subsequently, the effects of frequency lock-in, superposition and demultiplication on lift and drag are discussed based on the spectral analysis of time histories of lift and drag.
Keywords: Immersed-boundary method; Frequency effects; Oscillating cylinder; Lift and drag
Fig. 1. The drag and lift coefficients of a stationary cylinder at Re=200. (a) Comparisons of the time histories of the present computation with those of Guilmineau and Queutey (2002); (b) spectra of CL and CD.
Fig. 4. Snapshots of vorticity contours for a frequency lock-in case of f=0.202.
Fig. 5. Snapshots of vorticity contours for the flow around the oscillating cylinder at the moment when the center of the cylinder is located at the maximum negative displacement of the cylinder, for the three frequency lock-in cases: (a) f=0.18, (b) f=0.202 and (c) f=0.22.
Fig. 6. Snapshots of vorticity contours for the non-synchronization case of f=0.25.
Fig. 7. CL and CD for the non-synchronization case of f=0.25: (a) time histories and (b) spectra.
Fig. 8. Snapshots of vorticity contours for 
-subharmonic excitation of f=0.1 and A=0.15.
Fig. 9. CL and CD for 
-subharmonic excitation of f=0.1 and A=0.15: (a) time histories and (b) spectra.
Fig. 10. Snapshots of vorticity contours for 
-subharmonic excitation of f=0.1 and A=1.0.
Fig. 11. CL and CD for 
-subharmonic excitation of f=0.1 and A=1.0: (a) time histories and (b) spectra.
Fig. 12. Snapshots of vorticity contours for 1.5-superharmonic excitation of f=0.3.
Fig. 13. CL and CD for 1.5-superharmonic excitation of f=0.3: (a) time histories and (b) spectra.
Fig. 14. CL and CD for 2-superharmonic excitation of f=0.4: (a) time histories and (b) spectra.
Fig. 15. CL and CD for 3-superharmonic excitation of f=0.6: (a) time histories and (b) spectra.
Fig. 16. Snapshots of vorticity contours for 2-superharmonic excitation of f=0.4.
Fig. 17. Snapshots of vorticity contours for 3-superharmonic excitation of f=0.6.
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-subharmonic excitation
