Analysis Of The Performance Of Porous Structures In The Process Of Reducing The Action Of Wave Loads

In marine engineering,wave loads challenge the safety and service life of offshore oil and gas platforms,the infrastructure of offshore wind turbines,and coastal buildings.With the large-scale installation of offshore wind power,the problem of wave hazards to structures has become increasingly prominent,so reducing wave loads has received focused attention.Porous structures are widely used in breakwaters,but porous structures are less used in offshore platforms.The existence of porous plates provides an opportunity to reduce wave loads on offshore platforms,which is of great practical significance to improve the service life of offshore platforms and reduce costs.In this paper,a two-dimensional numerical wave pool based on the Navier-Stokes equations and VOF method is firstly established,the velocity boundary wave-making method and the push-plate wave-making method are implemented by UDF,and the second-order Stokes waves are simulated,and the wave dissipation area adopts a hybrid wave dissipation method combining the addition of damping terms and the stretching grid.The simulated and theoretical parameters are compared and analyzed for different locations and moments of the two waveform generation methods,and the results are in good agreement with the theoretical solutions.In addition,the influence of the hybrid wave dissipation method on the two wave creation methods in the simulation process is analyzed.According to the analysis results,the best applicable scenarios of the two wave creation methods are determined,and the velocity boundary wave creation method is selected accordingly for the subsequent work in this paper.Secondly,the numerical wave pool was extended in the combined wave-current and three-dimensional environments to improve the wave surface lift in the combined wave-current simulation and to determine the degree of influence of the z-directional grid division of the threedimensional numerical wave pool on the simulation results.Then,the validity of the parameters required for the porous jump boundary conditions obtained through theoretical calculations was studied,and the effects of eight porosities n and six thicknesses of the porous plate on the waves were analyzed,and it was determined that the thickness had no effect on the simulation results,so only the effect of porosity was considered in the subsequent work.Meanwhile,the interaction between waves and horizontal semi-submerged cylinder under three wave parameters was studied,and the relative error of simulation results under three schemes was analyzed,and it was determined that the wave parameter with the smallest wavelength had the smallest relative error.Under the above results,the interaction of waves with the cylinders under the semi-submerged horizontal porous circular walls was studied,and eight kinds of n and four kinds of pitch M were simulated,and the attenuation coefficients of horizontal/vertical wave force and wave force peak and valley values and wave force amplitude were analyzed to determine the downfall performance and the optimal downfall range of n and M.Finally,simulations were conducted for the interaction of waves with the vertical porous circular wall under the cylinder in a three-dimensional environment,and the attenuation coefficients of the horizontal wave force and wave force peak and valley values and wave force amplitude were analyzed for eight n and four spacing M working conditions to determine the load shedding performance and the optimal load shedding range for n and M.