The wake of two staggered square cylinders

Abstract

This work aims to provide a systematic experimental study of the wake behind two staggered square cylinders at a Reynolds number $Re=1.3\times 10^{4}$. Four distinct flow regimes, i.e. two single-street modes S-I and S-II and two double-street modes T-I and T-II, are identified based on extensive data, including Strouhal numbers $(St)$, flow structures and their downstream evolution. S-I, S-II and T-II are each further subdivided into two types. The flow characteristics in each regime are presented in terms of shear layer reattachment and impingement, vortex impingement, gap flow behaviour, interaction between cylinders and downstream evolution of the wake. A detailed discussion is made regarding how the physical aspects of the flow are connected to the initial conditions and the $St$ number.