Computational Approach to Identify Vortex Induced Vibration of Cylindrical Body

Abstract

Recent interest in utilization of sea water for new form of energy requires efficient intake system which often employs long riser through the ocean current. One of the major problems in the riser is the hydrodynamic forces which lead to so-called VIV (vortex induced vibration). This paper explores the computational method to resolve the flow structures around cylindrical body in the stream. FVM (Finite Volume Method) is applied for the oscillatory behavior of the cylindrical body. 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. One and two degrees of freedoms with damping and stiffness are considered with free oscillation under the influence of hydrodynamic forces caused by vortex shedding. Numerical approach to solve equation of motion of the body, Runge-Kutta method of 2nd order is employed. This study carried out for flows with low Reynolds numbers and found that the computed forces as well as the motion of the body are in good agreement with the previous studies. Depending on the flow condition, so-called lock-in phenomenon was also observed. This work was financially supported by projects of the &#8214 Development of Energy utilization technology with Deep Ocean Water&#8214 , KIOST of Korea.so-called VIV (vortex induced vibration). This paper explores the computational method to resolve the flow structures around cylindrical body in the stream. FVM (Finite Volume Method) is applied for the oscillatory behavior of the cylindrical body. 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. One and two degrees of freedoms with damping and stiffness are considered with free oscillation under the influence of hydrodynamic forces caused by vortex shedding. Numerical approach to solve equation of motion of the body, Runge-Kutta method of 2nd order is employed. This study carried out for flows with low Reynolds numbers and found that the computed forces as well as the motion of the body are in good agreement with the previous studies. Depending on the flow condition, so-called lock-in phenomenon was also observed. This work was financially supported by projects of the &#8214 Development of Energy utilization technology with Deep Ocean Water&#8214 , KIOST of Korea.