Numerical Simulation Of The Effect On Small-scale Marine Column Structure By Freak Waves

Extreme wave is one of the most important conditions that affect the normal operation and survival of marine engineering structures,freak wave is one of the most special extreme wave which has the characteristics of strong nonlinearity,high occurrence frequency,random and instantaneous.The huge wave load of freak waves will cause catastrophic damage to marine engineering structures.In view of the great harmfulness of freak waves,the study of the interaction between freak waves and structures has attracted the attention of many experts and scholars.The most common marine structures are column structures,which are characterized by small scale under most sea conditions,it is significant to study the numerical simulation of the interaction between freak waves and small-scale column structures.A 2D and a 3D numerical wave flume are constructed based on the Fluent software platform,which can simulate freak waves at the appointed time and location.A model of interaction between freak waves and small vertical columns is established by adding small vertical columns in the flume.The impact of freak waves,regular waves and two order Stokes waves on small vertical columns is compared.The related factors of impact effect are also analyzed.The main conclusions are as follows:(1)The simulated values of the freak waves in 2D and 3D numerical wave flume well fitted the theoretical value.The difference between the four characteristic parameters of simulated freak waves and the definition value is basically no more than 5%.(2)The wave force of the cylinder,the wave height in front of the cylinder and the dynamic water pressure on the surface of the cylinder increase significantly when cylinder is impacted by a freak wave,which are far greater than the regular wave and the two order Stokes wave.The cylinder is subjected to a very strong hydrodynamic pressure and the wave force of cylinder reaches the maximum value at the moment of freak wave impact.(3)The wave force of the cylinder,the wave height in front of the cylinder and the dynamic water pressure on the surface of the cylinder increase with the increase of the significant wave height,the peak period of spectrum and the diameter of the cylinder,theincrease of the freak wave is increasing.The location of the focus point has little effect on the maximum wave force of the cylinder,but affects the wave height in front of the cylinder and the dynamic water pressure on the surface of the cylinder.(4)The wave force of the square column,the wave height in front of the square column and the dynamic water pressure on the surface of the square column are greater than that of the cylinder.The maximum wave force of a square column is 1.57 times that of a cylinder.