Large eddy simulation of wake-induced vortex vibration of twin hangers of a suspension bridge

Twin hangers are used extensively in long-span suspension bridges. The downstream cables usually suffer wake-induced vibrations under strong wind or typhoon. Wake-induced vortex vibration of two tandem circular cylinders was numerically investigated by using a large eddy simulation (LES) method with Reynolds number from 1×104 to 4×104. The vibration characteristics and the variations of flow pattern with reduced wind velocity were studied. The coupling relationship of the dynamic response, the flow pattern and the aerodynamic for the downstream cylinder were discussed. Results show that the simulation results are in reasonable agreement with the wind tunnel test. At a certain reduced wind velocity, the downstream cylinder undergoes wake-induced vortex vibration at the largest magnitude. As the amplitude of the downstream cylinder increasing, the instantaneous phase of the displacement is ahead of that of the lift force and the lift does positive work in one cycle of the oscillation, and the phase difference between the displacement and the lift is gradually increased accordingly. Furthermore, the interactions between the wake of the upstream cylinder and the downstream one have two different ways, one is the vortice shed from the upstream cylinder interacting with the shear layer of the downstream cylinder while the downstream cylinder deviates from the equilibrium position, the other is the upstream vortice impinging on the windward surface of downstream cylinder while the downstream cylinder is near the equilibrium position. © 2019, Editorial Office of Journal of Vibration and Shock. All right reserved.