Suppression of the aerodynamic forces and vortex-induced vibration of a circular cylinder by bypass channels

Numerical investigations are conducted to evaluate the effectiveness of bypass channels in suppressing the aerodynamic coefficients of a stationary circular cylinder. The aerodynamic coefficients, which vary with the geometric shape, thickness, entrance location, and exit location of bypass channels, are given attention. Compared with the bare cylinder, the flow from bypass channels can weaken the cross-communication between the bilateral shear layers of the cylinder and suppress the alternating vortex shedding in the wake. Under the optimal parameters, the root mean square lift coefficient (Clrms) of a stationary cylinder can be reduced by more than 83.7% with a 60.1% reduction in the mean drag coefficient (Cdmean). Then, the vortex-induced vibrations (VIVs) of a single-degree-of-freedom spring-mounted cylinder are investigated under the optimal parameters. The results show that bypass channels are able to alter the vortex shedding pattern in the wake, disrupting the periodicity of lift fluctuations. Eventually, the maximal VIV amplitude of the cylinder with bypass channels can be reduced by 94.87%.