Numerical Study Of Hydrodynamic Characteristics Of Fiber Reinforced Plastics For Buoys Under Wave Loading

Firstly,in this paper a comprehensive overview is given about three-dimentional numerical simulation of waves and research development of hydrodynamic characteristics of buoys, especially a detailed description of the basic theory of the mathematical model is given.According to the method of Goda reflected waves and incident waves were separated, and a Fortan program was written to calculate the reflection coefficient Kr .A group of Mathematical models are established to study the relationship between the ratio of wave height and water depth(H/h),the reflection coefficient so that the optimal relationship between the reflection coefficient and H/h can be obtained.Based on the theory of the mathematical model numerical wave tank was established to simulate the wave and power-generating buoys,the mathematical model is verified,and obtained that the mathematical model can be applied to numerical simulations of various wave conditions and the numerical study of hydrodynamic characteristics of Reinforced Plastics for Buoys.Secondly, based on three-dimensional numerical wave tank wave propagation on the asymmetric step topography was simulationed. By the multiple times simulations,the results show that the pier flow on the asymmetric step topography is a complex three-dimensional fluid,and there was no obvious eddy structure on the positive side of the pier,high vorticity symmetrically gathered on the back side of the pier,some gathered on the positive side of the pier,a pair of vortex structures rotating in the opposite direction is generated on the back side of the pier.By comparing,KC is related to the period;but when the period is the same and wave height is differrent, the KC value is not very different, indicating that there is not obvious relationship bettwen KC value and wave height changes. Horizontal velocities change more severely in the positive side of the pier,change the most severely in the profile side, and because of the cover of the pier there is little variation in the back side of the pier. In the front and profile side of the pier there is significant vertical circulation, and there is no significant vertical circulation in the back side.Finally,a three-dimensional numerical wave tank was estabilished to study the simulation of the hydrodynamic characteristics of the fiber reinforced plastics for buoys and collapse phenomenon in the peak of the wave appeared in front of buoys;and obtained that the form of the free surface around the buoys,there wre many small folds in the free surface around the buoys,and shows obvious three-dimensional features.There was a whirlpool in the bottom left of buoys counterweight when instantaneous flow field was analysed,with the advance of the waves, the vortexes disappeared.there was a trend that vortexes was formed in the back side of the buoys,but the velocities was comparatively large,so there were not obvious vortexes.By analysis of the vortex structure it can be found that vortex structure asymmetric construction around the buoys was different from symmetric construction around the pier;when the vortex structure is not symmetry,there will be upward offset in the buoys and the buoys wriggled from side to side.By the analysis of vertical swing and longitudinal wigwagging it can be found that the performance of the fiber reinforced plastics for buoys in the stability of floating is superior to the all-steel buoys and the advantages in hydrodynamic characteristics is more obvious.Compare numerical results with the gravity center of buoy , the center of flotation,it will be found that the stability of the improved fiber reinforced plastics for buoys was relatively high.The hydrodynamic pressure in the vertical direction was maximum,the action of the hydrodynamic pressure must be considered in the design of the new type Fiber Reinforced Plastics for Buoys.