1.School of Naval Architecture,Ocean and Civil Engineering,Shanghai Jiao Tong University,Shanghai 200240,China;
2.School of Urban Innovation,Yokohama National University,Yokohama 2408501,Japan;
3.Collaborative Innovation Center for Advanced Ship and Deep-Sea Exploration,Shanghai 200240,China;
4.State Key Lab of Ocean Engineering,Shanghai Jiao Tong University,Shanghai 200240,China
Abstract：Both right cylinders and wavy ones’forced oscillations normal to incoming uniform flow under low Reynolds number (Re=150) were numerically investigated.The effects of oscillation amplitude and frequency on hydrodynamic forces exerted on these cylinders were examined.Their lock-in regions were determined and under lock-in states varying characteristics of lift force and wake were analyzed.The numerical simulation showed that although wavy cylinders can fully suppress Karman vortex street in static cases,the variation trend of their hydrodynamic forces with their oscillation frequency is similar to that of right cylinders under forced oscillation; wavy cylinders’suppressing lift and drag forces appear within lower and higher frequency regions,respectively; lift force curves have different performances under a lock-in state and a non-lock-in state; under a lock-in state,vortex modes in wake regions of right cylinders are controlled by oscillation frequency,2S and C(2S) modes are observed,while only one vortex mode is observed in wake regions of wavy cylinders.
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