Numerical study on aerodynamic drag and noise of circular cylinders with a porous plate

The wake control of the flow around a cylinder is a classic problem of fluid mechanics, which possesses a wide range of research foundations and applications. To attenuate the flow oscillation and resistance, this paper proposes a control strategy of cylinder flow based on an afterbody-attached porous material plate in the subcritical flow regime (Re = 1.4x10(5)). Three-dimensional numerical simulations are carried out by combining large eddy simulation (LES) with Ffowcs Williams-Hawkings (FW-H) acoustic analogy, and the validation is achieved through the available experimental and numerical data. Two configurations, namely the solid plate attached cylinder (SPAC) and the porous plate attached cylinder (PPAC), are dedicatedly compared. The results show that the PPAC has a remarkable effect on vortex shedding suppression and drag reduction. Especially, the PPAC even achieves a lift oscillation reduction by 97%, well above that by the SPAC. Meanwhile, both the reduction rates of resistance and lift fluctuation exhibit non-monotonic variations concerning the porosity, and their maximum effects appear at the porosity of 30% and 40% respectively. In principle, the PPAC greatly changes the separation pattern that the wake pressure elevates, turbulent kinetic energy decreases, and vortex core moves downstream, though the separation zone greatly enlarges. More importantly, the wake flow oscillation is significantly weakened. Besides, the OASPL around the cylinder is reduced by above 24 dB averagely by the PPAC with a porosity of 40%. (c) 2022 Elsevier Masson SAS. All rights reserved.