Characteristics of the surface pressure and energy input property of flexible circular cylinders experiencing vortex-induced vibrations.

A fluid-structure interaction (FSI) solver is developed to simulate the vortex-induced vibrations (VIVs) of flexible cylinders by coupling the large-eddy-simulation (LES) with the mode superposition method. The simulations included cylinders with different inclination angles (θ) in a uniform current and a vertical cylinder subjected to different sheared currents. The effects of the wake patterns on the surface pressures, spanwise correlation, and the powers of hydrodynamic forces are analyzed. It is observed that the vortex shedding along the inclined cylinders exhibited two distinct modes: straight vortex tubes and clip-shaped vortex tubes. With increasing θ , the fragmentation of the continuous straight vortices into smaller-scale clip-shaped vortices results in a reduction in surface pressure, thereby diminishing the promoting effect of the hydrodynamic forces on VIVs. For the sheared current cases, an increase in sectional current velocity leads to larger vortical structures. The hydrodynamic force within regions with higher vorticity magnitude promotes the VIVs; however, the cylinder encounters resistance from the ambient fluid and dissipated energy within regions that exhibits lower vorticity magnitudes. • The VIVs of flexible cylinders are simulated by integrating LES and mode superposition method. • The influences of the inclination angle and sheared currents on VIVs VIVare investigated. • The effects of vortex structures on the surface pressure and mean power of hydrodynamic force are analyzed. • The straight vortex has greater promoting effects on VIV than that of the clip-shape vortex for inclined cylinder. • The cylinder in the sheared current hinders structural vibrations by dissipating energy in regions with low vorticity magnitudes. [ABSTRACT FROM AUTHOR]