Flow control of a surface-mounted finite-length square cylinder using synthetic jets

This paper studied the effect of synthetic jets on active flow control around a finite-length square cylinder using the large eddy simulation method. Based on the oncoming flow velocity (U∞) and the model width d, the corresponding Reynolds number is 2.78 × 104. We explored the impact of the momentum coefficient (Cμ) and the dimensionless jet frequency (f*) on a finite-length square cylinder’s aerodynamic forces and flow field characteristics. The square cylinder has an aspect ratio of 5, with one end mounted on a wall and the other end free. The synthetic jet outlet is deployed at the windward leading edge of the square cylinder. It is found that synthetic jets positioned at the top can effectively suppress the cylinder’s aerodynamic forces. Both the momentum coefficient and dimensionless jet frequency influence the control effectiveness. The maximum reductions in total mean drag coefficients (Cd,mean) and fluctuating lift coefficient (Cl,rms) are 4.01% and 50.7%, respectively. With synthetic jet control, the shear flow at the free end of the square cylinder is significantly suppressed, the separation bubble on the top surface disappears, the shear layer at the free end approaches the top surface of the square cylinder, and the turbulent kinetic energy near the free end is significantly enhanced. This study may offer valuable guidance for related engineering applications.