Wake dynamics of steady flow past an obliquely oscillating cylinder at different Reynolds numbers

Steady flow past an obliquely oscillating cylinder at angles of attack θ (=0⁰, 45⁰, 90⁰) between the direction of body motion and incoming flow is investigated numerically over Reynolds number Rec from 100 to 855 and velocity ratio r*=Uw/Uc ranging from 0.1 to 2.0, where Uw is the maximum velocity of cylinder motion and Uc is the incoming flow velocity used to define Rec. The oscillation amplitude-to-diameter ratio A* is fixed as 0.4. It was found that the synchronisation between vortex shedding induced by steady flow and cylinder oscillation is primarily dependent on r* and weakly on Rec. The synchronisation states, which are primarily observed at intermediate r* (~0.30–1.50), have profound influences on the time-averaged in-line coefficients Cx.mean. At the small r* end, the force and wake characteristics resemble those of von Kármán vortex streets, except that significant force fluctuations in the motion direction are observed. At large r* values, the wake and force characteristics are similar to those induced by pure cylinder oscillations. The degree of wake three-dimensionality at small and large r* generally increases with ascending r* and Rec but lacks a clear variation trend with r* and Rec at intermediate r*.