Optimization of wavy cylinder for aerodynamic drag and aeroacoustic sound reduction using computational fluid dynamics analysis

Motivated by the requirement to lessen the aerodynamic drag and aeroacoustic sound of the bluff bodies, the present paper is devoted to a numerical analysis of the aerodynamics and aeroacoustics related with the flow past wavy circular cylinders. Based on the efficient flow control method, as has been presented by preceding researchers, the existing work embarks upon an investigation on the wavy cylinder at a various wavelength and amplitude conditions. Computations are performed for a circular cylinder of the length-to-diameter ratio (L/D) of 25 at a Reynolds number (Re) of 97300 using large eddy simulation and Ffowcs Williams- Hawking’s acoustic analogy. Firstly, the cylinder without waviness is subjected to a uniform incoming flow is considered for validation against measurements. Secondly, various collection of wave shape parameters, specifically dimensionless wavelength λ/D (=1 to 2.5), and wave amplitude a/D (=0.05 to 0.2) have been taken into consideration. It is disclosed that the proper selection of shape parameters could significantly reduce the drag and sound emission levels, compared to the normal cylinder. Finally, a multi-objective particle swarm optimization was performed using the radial basis neural network to simultaneously reduce the aerodynamic drag and sound emission, with λ/D and a/D as design variables. We recognized a critical λ/D and a/D for the wavy circular cylinder at the considered subcritical Re.