Numerical simulation of passive-suction-jet control of flow over two side-by-side circular cylinders.

A passive-suction-jet control scheme was adopted to manipulate the periodic vortex shedding of two side-by-side circular cylinders. The baseline case (both cylinders without control), Case #1 (only the lower cylinder was controlled), and Case #2 (both cylinders were controlled) were numerically simulated at five spacing ratios (S R) of 1.5, 2.0, 2.5, 3.0, and 4.0. The results show that the cylinders in all three cases experience a biased flow pattern at S R = 1.5 and 2.0 and tend to behave as isolated cylinders at S R > 2.0. The flow structures in Case #2 reveal that at S R = 1.5 and 2.0, the jets blown from the pipes roll up to form a large-scale vortex behind one cylinder and a series of small-scale vortices behind the other, eliminating the periodic vortex shedding of the two cylinders completely and yielding low fluctuating lifts. At S R > 2.0, the vortices formed by the jets weaken the influence of the wake vortices on the cylinders, contributing to a 94% reduction in lift fluctuation on average. Moreover, the holes centered at θ = 75°–135° were revealed to play an important role in continuously pouring positive vorticities into the fluid, which manipulate the periodic vortex shedding. • The control effectiveness of passive-suction-jet pipes on the flow over two side-by-side cylinders was examined. • The jets eliminated the periodic vortex shedding when both cylinders were controlled at spacing ratios of 1.5 and 2.0. • The lift fluctuation was reduced by 94% on average when both cylinders were controlled at spacing ratios lager than 2.0. • The boundary vorticity flux distribution reveals the control mechanism of the pipes. [ABSTRACT FROM AUTHOR]