Suppression of vortex shedding in the wake of a circular cylinder by attached permeable plates in deep water

The aim of present study is to control the vortex shedding downstream of a circular cylinder by means of attached permeable plates. Experiments were performed in deep water using Particle image velocimetry (PIV) and flow visualization techniques. The permeable plate was made of a chrome-nickel screen which was attached on the cylinder surface along its midspan. The main parameters of the study are porosity, β of the permeable plate, the plate angle, θ and the plate length, L/d. Within this context, six porosity values, eighteen plate angles and two plate lengths were defined and studied in order to examine their effects on vortex shedding control. The results showed that the use of a permeable plate with various plate angles suppresses the vortex shedding downstream of the circular cylinder by reducing the fluctuations in the wake, elongating the vortex formation region and attenuating the vortex shedding frequency. The porosity values of β=0.4 and 0.5 with plate angles of 45o≤θ≤135o were found to be effective on suppressing the vortical flow structure around the cylinder. Within these effective intervals, this study brings out a new approach on controlling the unsteady flow structure around bluff bodies and could be suggested for engineering applications concerning the vortex shedding and consequent Vortex-Induced Vibrations for deep water flow conditions.