Three-Dimensional Transition of the Flow Past a Cylinder Fitted with Helical Strakes

Helical strakes are the most employed devices to mitigate or suppress vortex-induced vibrations of circular cylinders. Although several investigations have been performed in order to predict the performance of these devices, proving its efficiency in specific configurations, little is understood regarding the physical mechanisms leading to the efficiency of these devices. Direct Numerical Simulation and three-dimensional global (TriGlobal) analysis of the flow around a cylinder fitted with helical strakes is performed at low Reynolds number in order to identify and understand more deeply the flow instabilities and physical mechanisms that mitigate and suppress the spanwise-correlated vortex-shedding.