VTechWorks staff will be away for the Memorial Day holiday on Monday, May 27, and will not be replying to requests at that time. Thank you for your patience.
Reduction of the Loads on a Cylinder Undergoing Harmonic In-Line Motion
Marzouk, O. A.
Nayfeh, Ali H.
MetadataShow full item record
We use the finite-difference computational fluid dynamics method to study in detail the flow field around a circular cylinder in a uniform stream while undergoing in-line harmonic motion. For a given motion amplitude, there exists a critical forcing frequency below which the lift and drag can be period-n, quasiperiodic, or chaotic. Similarly, for a given frequency, there exists a critical amplitude below which the lift and drag can be period-n, quasiperiodic, or chaotic. Above these critical conditions, the lift and drag are synchronous with the forcing. The lift nearly vanishes and the mean drag drops and saturates at a value that is independent of the driving frequency, whereas the oscillatory drag quadratically depends on it. We relate these features to changes in the wake and the surface-pressure distribution. We examine the influence of the Reynolds number on these critical frequency and amplitude. Second- and higher-order spectral analyses show remarkable changes in the linear and quadratic coupling between the lift and drag when synchronization takes place; it destroys the two-to-one coupling between them in the cases of no motion and synchronization due to cross-flow motion. (C) 2009 American Institute of Physics. [DOI: 10.1063/1.3210774]