Effect Of Waves On Special Structures Of Marine Pastures

In view of the increasingly active construction of Ocean Farm,and generally the harsh wave conditions in the marine environment,many components in the marine pasture structure can be simplified,such as simplified horizontal cylinder,upright cylinder,or diagonal cylinder.The pasture structures near the ocean surface are more violently affected by waves.Near the surface of the water,the interaction between waves and structures is complex,and there are few studies.In this paper,the numerical model of the interaction between waves and structures is used to study the wave force characteristics of simplified horizontal cylindrical structures,and to provide scientific guidance for the design and implementation of Ocean Farm.Firstly,the wave theory used in the numerical model is studied,including linear wave theory,nonlinear wave theory,extreme wave model and expression method research,etc.And the current research hot topic—extreme wave expression method,using constant steepness spectrum method,studied the characteristics of the extreme waveform described.Then,the boundary condition settings of the numerical wave model,grid convergence,and simulation verification of the interaction between the nonlinear wave and the horizontal fixed cylinder are studied.And determine the relative grid scale that can accurately simulate the interaction between waves and horizontal cylinders.Furthermore,using the numerical simulation technique in this paper;and study the regularity of the interaction between waves and horizontal cylinder in Ocean Farm,which can be simplified to horizontal cylinder.These include the effects of wave height,wave period,submerged water depth,and column diameter on horizontal wave force and vertical wave force.Finally,it points out the work that needs to be done in the future and the direction of further deepening,and provides guidance for related workers or follow‐up researchers.The research results show that:1)The method of constructing extreme waves with constant steepness without considering wave breaking,regardless of the high‐frequency and low‐frequency ranges,When thef_c is small the peak value of the highest wavefront increases significantly with increasing water depth;whenf_c(Median wave frequency range)is larger,the peak of the highest wavefront is not obvious with the increase of water depth;under the same water depth,thef_c smaller,the greater the peak of the highest wavefront.The greater the constant steepness Ga,the greater the maximum wavefront peak.The ratio of the highest wavefront peak to the second highest wavefront peak has nothing to do with water depth and Ga;the law of the relationship(35)f/f _c(the ratio of wave frequency range interval value than wave frequency range median)is significant.When(35)f/f _c<0.81 or(35)f/f _c>0.94,the ratio of the highest wavefront peak to the second highest wavefront peak increases with the increase,when 0.81<(35)f/f _c<0.94,the ratio of the highest wavefront peak to the next highest wavefront peak decreases with(35)f/f _cincreasing.2)When the relative size of the grid is R/Δx=10(the ratio of radius of the cylinder than the minimum space step),the numerical simulation results of the interaction between the wave and the horizontal column reach grid convergence.When the wave height is larger,the peak force on the horizontal column is greater and the valley value is larger.The larger the peak value is,the longer the wave period is,the smaller the peak force on the horizontal column is.The larger the water depth is,the less the effect of the depth on the wave and horizontal column.Between‐0.25m and 0.25m,the peak value of horizontal wave force is relatively large;when the column diameter becomes larger,the peak value of horizontal wave force and vertical wave force will also increase accordingly.The above research results of extreme wave characteristics and the interaction between waves and horizontal columns have important guiding significance for the design of the construction of horizontal columns in marine pastures.