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

Abstract

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 (SR) 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 SR = 1.5 and 2.0 and tend to behave as isolated cylinders at SR > 2.0. The flow structures in Case #2 reveal that at SR = 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 SR > 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.