Two Dimensional Numerical Analysis Of Flow Over A Circular And Square Cylinder And Vortex- Induced Vibration Of Rectangular Cylinder

Under certain Reynolds number, when the viscous fluid flows over the bluff body structure, the effect of adverse pressure gradient may cause the fluid boundary layer separate, and thus leads to periodic vortex shedding. Periodic vortex shedding will cause periodic aerodynamic force, if the structure is a self-vibration system, then it may arouse large displacement response, resulting in damage to structures. The analysis of flow over cylinder is the premise of studying vortex-induced vibration, so this article first studies flow over a circular cylinder and square cylinder under different Reynolds number, and then analyses vortex-induced vibration of three different aspect ratios of rectangular cross-section cylinders.Reynolds number is the crucial dimensionless parameter to determine the status of flow over cylinder, and it can be changed by variation of the speed of wind. For flow over a single circular and square cylinder, their two-dimensional numerical models of fluid region are first built, and the problem of flow over a single cylinder is numrical simulated using CFD software CFX from laminar region to supercritical region. After the applicability and accuracy of the numerical model for flow over a circular and square cylinder is proved, the law of parameters: lift coefficient, drag coefficient, strouhal number,, surface pressure distribution and the wake flow is systemly analysed and summaried.The phenomenon of vortex-induced vibration is often encountered in practical engineering problems, especially for the bridge towers, skyscrapers, offshore oil drilling platforms, chimneys and other tall structures, which can cause great damage. In this paper, the problem of vortex-induced vibration of rectangular cylinder is numerical simulated using ANSYS, Workbench and CFD software CFX. The solid part is simplified to two-dimensional mass-spring damper system, and the accuracy of the solid numerical models is verified. Maintaining the same structural parameters, the lock range is captured by changing the wind speed, and the lateral displacement response of rectangular cylinders in the locking range and non-locking range is analyzed and compared.