切り欠きを有する角柱の抗力低減のメカニズム

抄録

Mechanism of drag reduction acting on a rectangular cylinder with recessed corners at its front edges was investigated in a low speed wind tunnel by means of flow visualization and PIV technique. The aspect ratio of the recessed corner h/t was changed for rectangular cylinders with aspect ratio of ranging from 0.45 to 2.05. As an indicator of drag reduction, the back pressure of the rectangular cylinders was measured. The results show that the back pressure increases to the maximum value for all rectangular cylinders when h/t is about 1. The flow visualization reveals the mechanism of the drag reduction as follows. The edge of the recessed corners makes the separated shear layer turbulent. It results in suppressing the vortex formation in the wake behind a cylinder. This vortex suppression reduces the curvature of the separated shear layer from the other side of the cylinder and increases the back pressure. As the result, drag of the rectangular cylinder is decreased.