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Wind and Structures
  Volume 26, Number 4, April 2018 , pages 215-229
DOI: https://doi.org/10.12989/was.2018.26.4.215
 


Large eddy simulation of flow around a stay cable with an artificial upper rivulet
Yan Zhao, Xiaoqing Du, Ming Gu, Xiao Yang, Junjun Li and Ping He

 
Abstract
    The appearance of a rivulet at the upper surface of a stay cable is responsible for rain-wind-induced vibration (RWIV) of cables of cable-stayed bridges. However, the formation mechanism of the upper rivulet and its aerodynamic effects on the stay cable has not been fully understood. Large eddy simulation (LES) method is used to investigate flow around and aerodynamics of a circular cylinder with an upper rivulet at a Reynolds number of 140,000. Results show that the mean lift coefficients of the circular cylinder experience three distinct stages, zero-lift stage, positive-lift stage and negative-lift stage as the rivulet located at various positions. Both pressure-induced and friction-induced aerodynamic forces on the upper rivulet are helpful for its appearance on the upside of the stay cable. The friction-induced aerodynamic forces, which have not been considered in the previous theoretical models, may not be neglected in modeling the RWIV. In positive-lift stage, the shear layer separated from the upper rivulet can reattach on the surface of the cylinder and form separation bubbles, which result in a high non-zero mean lift of the cylinder and potentially induces the occurrence of RWIV. The separation bubbles are intrinsically unsteady flow phenomena. A serial of small eddies first appears in the laminar shear layer separated from the upper rivulet, which then coalesces and reattaches on the side surface of the cylinder and eventually sheds into the wake.
 
Key Words
    rain-wind-induced vibration; numerical simulation; upper rivulet; friction; separation bubble
 
Address
Yan Zhao, Xiao Yang, Junjun Li and Ping He: Department of Civil Engineering, Shanghai University, No. 99 Shangda Road, Shanghai, China
Xiaoqing Du: Department of Civil Engineering, Shanghai University, No. 99 Shangda Road, Shanghai, China;
Wind Engineering and Aerodynamic Flow Control Research Center, Shanghai University, No. 99 Shangda Road, Shanghai, China
Ming Gu: State Key Laboratory for Disaster Reduction in Civil Engineering, Tongji University, No. 1239 Siping Road, Shanghai, China
 

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