Numerical Simulation Of Flow Around Rotationally Oscillating 2-d Plates

The simulation of bluff body with moving boundary and to control the wake flow of bluff body is important issue in computational wind engineering. In this paper, numerical simulation of flow around the rotationally oscillating plate was carried out, in order to obtain qualitative rules and make pre-research for designing active simulation devices.The development on the research of flow around flat plate and the dynamic mesh technology in CFD simulation was systematically reviewed in this paper. The numerical model was obtained by embedding the motion code of the rotationally oscillating plate through the User Defined Function (UDF) in Fluent. To investigate the aerodynamic characteristics of the rotationally oscillating plate and the characteristics of wake flow, several numerical schemes have been tested with different amplitudes and frequencies. The main research contents were presented as follows:1. A numerical simulation of flow around a square cylinder at a Reynolds number Re=22000 was carried out. It has a great consistency with published research in drag coefficient and Strouhal number. The model in this paper was validated. Simultaneously, a numerical simulation of circular cylinder oscillating transversely in a uniform stream was practiced. The lock-in and beat phenomenon was observed, which verified the feasibility of simulating moving boundary issues by using dynamic mesh.2. The aerodynamic characteristics of the rotationally oscillating plates which placed along the flow and orthogonal to the flow were compared. The average wind speed and turbulence intensity of the wake flow were also researched. The results show that the turbulence intensity increases as the amplitude increases, and decreases as the frequency increases when the plate placed along the flow. When the plate placed orthogonal to the flow, the turbulence intensity increases at the first and then decreases as the amplitude increases.3. The characteristics of flow around the combination plate which could be applied in the wind tunnel were investigated with different amplitudes and frequencies. According to comparison of the flow characteristics of two parallel combination plates with different spacing ratio, two different wake flow modes were found. The results show that the turbulence intensity at near wake region could be strengthened by decreasing the amplitude and increasing the frequency. The turbulence intensity with two parallel combination plates is larger than that with a single combination plate at the same amplitude and frequency. As the spacing ratio increases, the turbulence intensity at near wake region decreases. When the spacing ratio is small enough, the grap flow between two plates would be biased to one side. This calculation provided references for the application of the oscillation-based active simulation devices in the wind tunnel.