NUMERICAL STUDY OF VORTEX INTERACTIONS BEHIND 2 CIRCULAR-CYLINDERS INBISTABLE FLOW REGIME

A two-dimensional discrete-vortex model was used to investigate vortex interaction inside the near wakes of two circular cylinders in side-b y-side arrangement within bistable flow regime. Two phases of vortex e volution are mainly identified in the near wakes: a symmetric shedding phase, characterized by two antiphase vortex streets, and a flip-flop ping phase, characterized by biased gap flow, switching at irregular i ntervals. For the hip-hopping phase, vortex amalgamation, vortex pairi ng and dipole are found. Vortex dynamics of the flow is presented and its possible effects on the flow parameters are discussed. The initiat ion and transition from the symmetric to flip-flopping phase are cause d by the asymmetry of one of the gap vortices. Flow visualization and quantitative results obtained seem to support the findings from the mo del.