Flow Characteristics of Cylinders with Asymmetric Grooves: A Modeling and Experimental Study

This study examined the drag reduction properties of cylindrical flows across various asymmetric notched structures through numerical simulation and particle image velocimetry. The focus was on investigating the influence of the number of asymmetric grooves on the drag characteristics, including the mean drag, spectral characteristics, time-averaged streamlines, separation point prediction, time-averaged pressure, wake vortex strength, Reynolds stress, and turbulent kinetic energy. The results showed that the presence of asymmetric grooves significantly influenced these flow parameters. Notably, the improvement was optimal in the four-groove configuration, evidenced by the lowest mean drag coefficient (0.804), vortex shedding frequency (2.74 Hz), recirculation area length (1.208D), and pressure difference across the cylinder (81.76). Moreover, this configuration resulted in the weakest trailing vortex, a 45% reduction in the maximum Reynolds stress (0.011), and a 40.5% decrease in the maximum turbulent kinetic energy (0.05). Thus, the presence of asymmetric grooves had a significant positive effect on the cylindrical flow properties, though the degree of improvement decreased with further increase in the number of grooves.