Flow Structures Around a Finite Wall-Mounted Cylinder Having an Inclined Hole

To study the effect of a hole on the wake structures of a low aspect ratio circular cylinder, an inclined hole going from the front face to the top end face is drilled inside cylinder having height H and diameter D of 70 mm (an aspect ratio H/D = 1). In order to compare the flow structures between the hole and no-hole cylinders, the PIV measurement of Reynolds number of 8,570 is carried out in a water tunnel. Furthermore, to evaluate the position effect of the hole, three kinds of the hole cylinders having different height of hole from the flat plate are used. It was found that the separation region of the hole cylinder on the top face is evident smaller than that of the standard cylinder. An area of a high negative u-component velocity was observed in a rear recirculation region by using the hole, indicated a strong separation flow. The Reynolds shear stresses were evidently suppressed by the blowing flow from the hole, but their distribution spread out.