Numerical Study On Hydrodynamic Characteristics Of Water Wave Transformation And Evolution Over Porous Seabed

In nature,seabed is of porosity because they are usually composed of various types of sand gravel,which results in the change of wave parameter,such as wave length and wave height.So the permeability of seabed should not be neglected.Besides,the stability of the beach is also affected by the interaction between waves and the permeable seabed.Therefore,it is of great significance to study the propagation and evolution of water waves on the permeable seabed in the field of coastal engineering.Based on the permeability of seabed,this paper studied the propagation and evolution characteristics of waves over two-dimensional permeable seabed using a numerical wave model.Based on open source software OpenFOAM,a numerical model is developed to describe the propagation evolution of waves over the permeable seabed.However,the serious wave height attenuation along the flume without porous seabed is encountered,which will greatly affect the accuracy of the subsequent calculation of wave height attenuation over the permeable seabed by the model.Based on this problem,firstly,by adjusting the grid quality,calculating the time step,replacing other traditional turbulence models,wave generation theory and interpolation format,it is found that the wave attenuation along the flume has not been significantly improved.Considering that the traditional turbulence model may cause excessive dissipation,the IHFoam solver only contains several traditional turbulence models,in the end the excessive wave damping is avoided by introducing a new turbulence model with additional buoyancy correction term.The validity of the numerical model is verified by the simulation of the physical model of wave propagation over the porous seabed and porous dam break.The calculated results present great agreement with the experimental results,which proves that the numerical model has the ability to accurately simulate the propagation evolution of waves over the permeable seabed.In the end,parametric analysis is carried out based on this model.The effects of wave nonlinearity,wave length,thickness of permeable seabed,porosity,median particle size and intrinsic permeability of porous media on wave height attenuation over permeable seabed and flow field distribution in porous media are studied and concluded.Besides,the reasonable selection of linear and nonlinear drag coefficients is very important for correctly simulating the propagation and evolution characteristics of waves over the permeable seabed.So the sensitivity of wave height attenuation and the flow field in the permeable seabed to linear and nonlinear resistance coefficients is studied,which provides reference for the reasonable selection of resistance coefficient.