THREE-DIMENSIONAL WAKE STRUCTURES OF FLOW AROUND AN OSCILLATING CIRCULAR CYLINDER

摘要

Direct numerical simulationsthe three-dimensional flow around an oscillating circular cylinder are carried out. Imposed body oscillations are realized for low amplitude of oscillation, A/D = 0.4 and for high amplitudes, A/D = 1.0.As the intention is to analyze the amplitude influence in the wake dynamics, the frequency of oscillation is fixed and chosen to be inside the lock-in region, 0.95fs, where fs is the shedding frequency of fixed cylinder. The three-dimensional wake characteristics of the oscillatory body simulations are compared to the fixed body. Floquet stability analysis of two-dimensional oscillatory flow is carried out to complete the investigation and consistently analyze the three-dimensional flow results. The different unstable modes are identified for each of the cases, and they are found to depend basically on the vortex patterns.