Three-dimensional flow structures around a finite wall-mounted cylinder controlled by using an inclined hole

Three-dimensional flow structures around a finite wall-mounted cylinder, which is drilled an inclined hole going from the rear surface to the top surface inside a circular cylinder of an aspect ratio 1 (RIH), are instantaneously measured by Tomographic PIV in a water tunnel. Here both of the diameter D and height H of circular cylinder are 70 mm. Tomographic PIV measurement was performed at Reynolds number of 8,570 in a water tunnel. Three dimensional time-mean velocity fields, vorticity and Q criterion are discussed and compared between the hole and no hole of low-aspect-ratio cylinders. It is found that RIH generates a stronger counter-rotating vortex pair near the free end and a stronger downwash flow behind the RIH cylinder. Comparing to the standard cylinder, the arch vortex and large-scale vortices break down slowly in the wake of RIH cylinder.