Geometrical parameter analysis on stabilizing the flow regime over a circular cylinder using two small rotating controllers

Vortex shedding behind a cylindrical structure decreases its lifetime. Different active and passive methods have been proposed for suppressing the shed vortices. Two small rotating cylinders installing near to the main cylindrical structure can be actively used for this purpose. In the present research work, the impacts of the geometrical parameters on the effectiveness of the two rotating controllers, which were symmetrically installed neighbor to the main circular cylinder, have been numerically studied at a particular laminar flow regime. A finite volume approach has been used to simulate the unsteady flow around cylinders. Numerical computations illustrated that, both the main cylinder and its adjacent rotating controllers might be subjected to oscillatory forces. Also, numerical results showed that if rotating controllers were installed at an appropriate position, oscillatory exerted forces on the system of cylinders might be completely suppressed and flow regime became stable. Besides, the exerted drag forces on the main cylinder and also rotating controllers decreased when rotating controllers were installed at this particular position. Meanwhile, extensive analyses on the details of the flow field have been presented to discuss the mechanism of re-stabilizing the flow regime.