Experimental Flow Control Around Circular Cylinders with Porous Media Coatings

Abstract

Flow structures have been experimentally obtained for the circular cylinders with porous media coatings (PMC) at Reynolds number values from Re = 5000 to Re = 10,000. Furthermore, flow characteristics have been exhibited for different contour graphics and the velocity profiles have been indicated at four downstream stations. The regions having minimum streamwise velocity component values approached the circular cylinders by increasing Reynolds numbers. Nevertheless, it is not valid for the cases of PMC1 and PMC2 from Re = 7500 to Re = 10,000. Because of the separated flows from the upper and lower cylinder surfaces, the maximum streamwise velocity components have been attained. The same effect has been observed for the cross-stream velocity component values, and these clusters approached the circular cylinders. As expected, the flow separations caused wake fluctuations. Nonetheless, the cluster sizes have also been decreased by the decrement of Reynolds numbers. It is significant for the occurrence of turbulence intensity in the wake regions of the circular cylinders. However, there is no obvious difference between the bare cylinder and the PMC3 in terms of flow patterns. Another important result is that the coating effect is explicitly exhibited by the increase in Reynolds numbers. As explained by the velocity values, these zones moved away from the bodies due to the decrement of Reynolds numbers. As a parameter, Reynolds number is considerably dominant on the cluster positions. Similar patterns have been approximately observed for PMC1, PMC2 and PMC4 in terms of Reynolds stress correlations.