Navier-Stokes 식을 이용한 회전 진동하는 2차원 원형 실린더 주위 유동해석

Abstract

Although the geometry of circular cylinder is simple, the flow is very complicated because of flow separation and vortex shedding. Despite the research for flow over a circular cylinder has been numerically and experimentally carried out, the flow has not been clarified even now. It has been known that the vortex shedding from a circular cylinder can make unsteady flow and cause a structure to vibrate. The most important phenomenon is Lock-on for the flow analysis around an oscillating circular cylinder. The lock-on phenomenon showed that when the oscillation frequency of the circular cylinder is at or near the frequency of vortex shedding from a stationary cylinder, the vortex shedding synchronizes with the cylinder motion. This phenomenon can be recognized by the spectral analysis of the lift coefficient history. At vortex Lock-on region the shedding frequency is modulated to the body frequency and a single peak appears in the frequency analysis. In this paper, it were analyzed the relation between the oscillating frequency of rotary oscillation circular cylinder and the vortex shedding frequency. In particular, the frequencies of the lift and drag coefficient are compared with the frequency of rotary oscillation at lock-on and non-lock-on region. The frequencies of rotating oscillation are near the Strouhal number of the flow around a stationary circular cylinder at Mach number of 0.3 and Reynolds number of 1000, and the maximum oscillating angles are 5º, 8º, 10º and 17º.