Investigation on aerodynamic characteristics of upper rivulet on stay cable using large eddy simulation

The formation of upper rivulet is crucial to the occurrence of rain-wind induced vibration (RWIV) of stay cables. To understand the formation mechanism of the upper rivulet, which is still unclear, the aerodynamic characteristics of the upper rivulet were investigated using large eddy simulation (LES), which is hard to implement in wind tunnel tests. The mean pressures and skin friction on the rivulet were obtained at different rivulet position. Results showed that the friction-induced aerodynamic forces on the rivulet have the same order in quantity as the pressure-induced forces, which cannot be neglected when clarifying the mechanism of the rivulet formation. Under a certain range of wind velocity, due to the resultant of skin friction and pressure, the upper rivulet can stand on the positions where the cable aerodynamics may dramatically change. To the best of our knowledge, it is the first study to obtain the friction aerodynamic forces acting on the upper rivulet, which is very useful to developing more rational theoretical models of RWIV in the future.