Interaction of free oscillating flat plate and VIV of a circular cylinder in laminar flow

Abstract

The Flow-Induced vibration around bluff bodies is always of great interest in terms of control and suppressing the motion or amplifying and harvesting energy and the flat plates are known as useful means to make proper changes in flow structure. The objective of this paper is to investigate the effect of a downstream flat plate with one degree of freedom on the wake structure and FIV of an upstream circular cylinder in laminar flow. Numerical simulation is used to simulate the two-dimensional incompressible flow around two rigid objects with identical characteristic lengths and a variable horizontal spacing in a range of 0.5D≤G≤4D to focus on the near wake and interaction of two objects. The results show that a free to vibrate flat plate located in the wake of a rigid cylinder not necessarily plays the role of a splitter in the near wake and starts to vibrate in an even small spacing such as G =1.5D. The Recirculation zone structure and its length are found to be the main reasons for induced vibration in such close configurations. In the case of simultaneous free oscillation, reducing the horizontal gap amplifies the amplitude of both objects. The interaction of the oscillating plate and the shear layers results in vortices with more strength that affect both objects. This amplification in oscillation amplitude shows that the present concept has a considerable potential to be utilized in the design of an improved energy harvesting system by converting fluid dynamic energy into electric energy from independent objects in a small area.