Drag Reduction Of A Finite Circular Cylinder With A Boxfish-Like Extended Surface

In numerous aerodynamic applications, the greater drag coefficient of the bluff body in transitional flow, i.e., at subcritical Reynolds numbers, is one of the most significant problems. Current research focuses on the drag reduction of a circular cylinder by utilizing a passive technique, both numerically and experimentally, for the subcritical Reynolds number with a range of 8.85×104 to 1.98×105. Initially, the frontal shape of the Boxfish was considered an extended surface and had a detrimental effect on drag reduction. Later, a modified design of the frontal part of the Boxfish is considered as an extended surface, and studies are carried out for three stem lengths (distance between the extended surface and cylinder) with a wide range of angles of attack. At an attack angle of 0°, a stem length of 80 mm reduces drag by 71% compared to a cylinder with no stem. Where 33% of the results integrating angle of attack were reduced at 5° angle of attack and 70 mm stem length, Current research suggests that a stem length of 80 mm reduces drag across a broad Reynolds number range. Numerical and experimental data indicate that boundary layer detachment and reattachment, as well as wake generation, decrease drag. Hence, offering a proposed design for future vehicles that generates less drag, thereby reducing environmental pollution.