不同排列方式下双方柱绕流的同步现象及相位特征研究

Synchronization modes of the flow around two square cylinders with different pitch ratios (P^*=1.5~5.0, where P^*=P/D, P is the centroid spacing of the square cylinder, and D is the side length of the square cylinder) and incidence angle (α=0°~90°) are investigated using two-dimensional direct numerical simulation at Re=100. The characteristics of lift coefficients are analyzed by using spectrum analysis methods and phase dynamics theory, following by a discussion on the identification of flow synchronization and the wake evolution of the square cylinders. The effects of P^* and α on the synchronization modes, phase dynamics and transition patterns are then examined. The 1/1, p/p (p is a positive integer greater than 1) and p/q (q is a positive integer not equal to p) synchronization modes, quasiperiodic mode and desynchronization mode of flows are observed, corresponding to the phase locking, phase trapping, phase drifting, phase drifting and slipping, as well as other states, respectively. When α≤35°, the 1/1 synchronization is the dominant mode in the regime map. When α>35° and P^*>2.5, most of the cases are quasiperiodic modes, while those are mainly characterized by the desynchronization mode when α>35° and P^*≤2.5.