Experimental study for wake manipulation of structured porous square cylinder*

The purpose of this study is to experimentally explore the role of permeability of a structured porous cylinder with respect to the wake structure shed from the cylinder and its corresponding aerodynamic features. To this end, an addictive manufacturing technique was utilized to fabricate the porous cylinder that was comprised of a simple cubic lattice structure.  This unique manufacturing technique coupled with a simplified lattice structure allows to decouple the permeability of the porous cylinder from the porosity. Therefore, in this work, a fundamental and systemic study was performed to reveal the influence of permeability of the porous cylinder on the flow pattern behind the cylinder and its resulting aerodynamic force acting on the cylinder.

In this study, permeabilities of porous cylinders which porosity was fixed at 0.7 were carefully measured in an open-loop pipe flow system with a highly accurate differential pressure transmitter and a thermal mass flow meter. Based on these permeabilities, flow pattern induced by structured porous square cylinders (D=40 mm) and their aerodynamic features at moderate Reynolds number were acquired by particle-image velocimetry and three-component balance unit, respectively.