Simulation Of Solitary Wave Propagation And Runup Over Fringing Reefs

In recent years,the ability of coral reefs in resisting marine disasters has aroused wide concern.Although many scholars did a lot of researches on the propagation characteristic and influence factors of the waves on coral reef topography in different methods,there is still a lack of understanding on the propagation and runup of the solitary wave on fringing reefs which can simulate the first wave of tsunami.In this paper,the propagation and runup experiments of solitary wave over fringing reefs have been carried out in a two-dimensional wave tank.The results showed that solitary wave did not break through the forereef slope and the reef flat when the ratio of wave height to total water depth was small,and the runup on the backreef slope was nearly 4 times of the incident wave height.When the ratio of wave height to total water depth increased to a larger value,the deformation of the solitary wave was obvious when it propagated on the forereef slope and it broken at the rear of the reef,and the runup on the backreef slope was nearly 2 times of the incident wave height.Meanwhile,a fully nonlinear Boussinesq wave model Funwave-TVD was utilized in this study.By compared with the experimental data,sensitivity of the bottom friction coefficient and grid size was investigated to elucidate the model performance.The results showed that this numerical model could accurately simulate the solitary wave propagation and runup over fringing reefs by choosing the appropriate bottom friction coeff-icient and grid size.Then,the calibrated model was then applied to study the effects of different morphological and hydrodynamic parameters on the solitary wave propagation and runup.The results showed that the maximum runup height increases significantly as incident wave height increases,although the solitary wave breaks more violently with larger incident wave height.The maximum runup height decreases significantly as the bottom friction coefficient increases and the bottom friction mainly influences the wave attenuation over the reef flat and backreef slope.The maximum runup height also decreases significantly with the increase of the reef-flat width,however,when both the reef-flat width and bottom friction coefficient are very small,the maximum runup height may increase with the increase of the reef-flat width.The maximum runup height increases gradually as the reef-flat submergence increases and is insensitive to the forereef slope angle while it decreases significantly as the backreef slope gets mild.