Vortex-induced vibration of two circular cylinders in a side-by-side arrangement at moderate Reynolds number: A numerical study

Abstract

Vortex-induced vibration (VIV) of two transversely vibrating cylinders in a side-by-side (SBS) arrangement is numerically investigated using a combination of direct-forcing immersed boundary and large eddy simulation techniques. The VIV responses of vibrating SBS cylinders at two reduced velocities (UR* = 4.0 and 6.0) are studied for a range of gap ratio 1.0 ≤g*≤ 3.0. Moreover, the influence of mass ratio, damping ratio, and Reynolds number in the amplitude response and efficiency of VIVACE (Vortex-Induced Vibration for Aquatic Clean Energy) from vibrating SBS cylinders are investigated at moderate Reynolds numbers (Re = 1000 and 10 000). The optimal gap ratio for UR* = 4.0 is in the range of 1.0 ≤g*≤ 1.2. Larger than this range, the VIV responses are close to single-cylinder responses. At UR* = 6.0, all gap ratios show lower responses than a single-cylinder case. The vibrating SBS cylinder with a larger damping ratio results in higher maximum VIVACE efficiency with a narrower UR* range for significant efficiency. With almost the same amplitude response, the SBS cylinders with a lower mass ratio result in lower VIVACE efficiency. Using the same mass-damping parameters, it appears that a low mass ratio could be desirable to increase the UR* range of significant VIVACE efficiency and pick the proper damping ratio to reach a high value of maximum VIVACE efficiency. The effect of flow conditions on the amplitude response and VIVACE efficiency of vibrating SBS cylinders with the same VIV parameters is not significant.