Passive Vibration Reduction in Circular Cylinders: The Role of Slits

Abstract

This work investigates a passive flow control method to mitigate vortex-induced vibration (VIV) by introducing a slit into a circular structure. The impact of varying slit sizes on the behaviour of a cylinder subjected to VIV is investigated across different reduced velocities (Ur) at a Reynolds number (Re) of 100. The size of the slit (S/D) is adjusted from 0 (without slit) to 0.1 & 0.2, where S corresponds to the width of slit & D the cylinder diameter. The mass and damping ratios are fixed at m* = 10 and ζ = 0.005, respectively, while Ur is varied from 2 to 10. The numerical analysis is conducted using Ansys/Fluent, incorporating mesh motion to consider cylinder vibration. The outcomes are presented in terms of vibration amplitude & frequency, drag & lift coefficients, Strouhal number, and vorticity contours. The findings suggest that the slit reduces lift and drag coefficients, effectively suppressing VIV. Examining maximum vibration amplitude, a 10% slit results in a 5.16% decrease, whereas a 20% slit leads to a substantial 34.27% reduction compared to a solid cylinder.