Aerodynamic Instability of Circular Slender Structures Due to Bistable Flow Activity

Slender structures with circular cylindrical cross-sections are very common in civil engineering, industrial equipment and bridge engineering. Such long cylinders subjected to wind columns, piles, cables, chimney, pylons others. On an instability called dry galloping has been recently theorized be linked unpredictable jump state occurring once the boundary layers of cylinder changes from laminar turbulent. With a non-stationary character, force generated at critical flow regime is named bi-stable activity. In this work, birth activity around made high-density polyethylene studied experimentally tunnel. The pressure pattern linearly decomposed geometric modes governing as function circularity defect created. results show that energy load observed depends strongly on defect. Furthermore, inclination angle 60° confers significant increase mode when unsteady asymmetric reattachment event occurs. paper also highlights variability mean drag coefficient macroscopic