저 레이놀즈 수 유동장에서의 원형실린더 VIV 해석

Abstract

In many ocean engineering, vortex induced vibration of slender structures such as riser has long been a nemesis to be investigated and yet to be fully understood. Numerous experimental and computational studies approaches have revealed the many aspects of the phenomenon and tried different measures for mitigation of the related damages. However, due to complexity of interaction between deformable structure and unsteady hydrodynamic forces, both experimental and computational models are not easy tasks. In this study, a computational fluid model is applied to simulate the unsteady flow passing the circular cross section while the body is freely moving under the influence of hydrodynamic forces caused by vortex shedding. Finite volume method is utilized. In order to implement the movement of the body influenced by the hydrodynamic force, meshes around the moving body are reconfigured considering the new location at every time step of computation. Both mechanical damping and stiffness are assumed when the equation of motion of the oscillatory body is solved at every time step. In addition, vortex shedding of frequency near the natural frequency of the structural system clearly reveals the lock-in behavior.many aspects of the phenomenon and tried different measures for mitigation of the related damages. However, due to complexity of interaction between deformable structure and unsteady hydrodynamic forces, both experimental and computational models are not easy tasks. In this study, a computational fluid model is applied to simulate the unsteady flow passing the circular cross section while the body is freely moving under the influence of hydrodynamic forces caused by vortex shedding. Finite volume method is utilized. In order to implement the movement of the body influenced by the hydrodynamic force, meshes around the moving body are reconfigured considering the new location at every time step of computation. Both mechanical damping and stiffness are assumed when the equation of motion of the oscillatory body is solved at every time step. In addition, vortex shedding of frequency near the natural frequency of the structural system clearly reveals the lock-in behavior.