Numerical Simulation Study On The Protection Mechanism Of Floating Breakwater To Coastal Columnar Structure

With the development of dredger to be large-scale and high-efficient,the safety issue of mud pipeline on its hull structure has become an important research topic.Previous studies have measured the load on the structure under different wave conditions,but how to reduce the load has not been explored.In order to adapt to the weak foundation,maintain the exchange of sea water,ensure the low cost and meet the needs of convenient placement,the floating breakwater as a temporary cover is a practical engineering measure.Based on Navier-Stokes equation and a new six degree of freedom algorithm,this paper establishes a two-dimensional hydrodynamic numerical model of the interaction between rigid floating body and fluid.The model used high precision Level set method to distinguish the water-air interface,combining it with the immersed boundary method studies the hydrodynamic characteristics of floating breakwater under wave action and analyzes the complex flow field of wave impacting coastal structures under the protection of floating breakwater.Effects of prominent parameters,i.e.wavelength,wave height,water depth,aspect ratio of breakwaters,submersion depth,spacing distance between breakwater and the structure,and the degrees of freedom of floating body,on the performance of floating breakwater and reducing the hydrodynamic load on structures are systematically analyzed.It is found that the hydrodynamic numerical model established in this paper can well capture the hydrodynamic changes during the interaction of regular waves with floating bodies and structures,and has high accuracy;the floating breakwater can effectively reduce the magnitude of horizontal and vertical loads on horizontal structures,and with the increase of incident wave length and the decrease of wave height,the attenuation of the wave absorbing ability relevant to floating breakwater results in the increase of wave transmission coefficient.Under the condition of the same incident wave height,the vertical motion of the floating breakwater is stable relatively;As the height and density of the floating body increase,the heave height of the floating body and the wave energy consumption increases,and resulting in the decrease of wave transmission coefficient.With the increase of the wave period,the protective effect of the fixed floating breakwater is better.