Study On Propagation Characteristics Of Oblique And Multidirectional Waves On Slope

The study of near-shore wave propagation is one of the important topics of coastal hydrodynamics.In the near-shore water depth,a variety of ports,protection embankment and bank revetment works are constructed,in this zone the terrain is general slope,and the waves are mostly oblique or multidirectional irregular waves.Therefore,it has important theoretical significance and engineering application value to carry out the study of the propagation characteristics of oblique and multidirectional waves on the slope.In this paper,the propagation characteristics of normal,oblique and multidirectional waves under the conditions of 1:15 slope are systematically studied with the physical model experiment.The main contents and achievements are as follows:The propagation process of the normal,oblique and multidirectional waves on the slope is comparatively studied.Whether for the regular waves,or the irregular waves,there is little difference for water surface series,breaker types and the periodic variation,and the wave height is compared with the dimensionless method.The comparative results show that the growth of the normal wave is larger than that of the oblique wave when the period is small.The breaker indices of the normal,oblique and multidirectional waves on the slope are comparatively studied.The breaking indices are divided into four categories according to wave types and slope conditions.Their general forms and coefficients are summarized.The analyzed results show that under the same conditions,the breaker indices of oblique waves are larger than that of normal waves.The breaker indices defined with significant wave height of irregular waves is lower than that of regular waves,and breaking wave height of multidirectional waves is lower than normal irregular waves for larger waves.The wave spectra of the normal,oblique and multidirectional waves on the slope are comparatively studied.The oblique and normal regular waves are analyzed by third-order harmonics,and the values of the double frequency changes are similar.The energy transfer of the oblique irregular waves during the climbing process is more obvious than that of the normal irregular waves.There are some differences in the spectrum variation between the multidirectional and normal irregular waves at different period.The wave height distribution of the normal,oblique and multidirectional waves on the slope is comparatively studied.They are mainly in comparison with the Rayleigh distribution and the Glokhovskiy distribution,which deviate from the Rayleigh distribution in the propagation process and tend to be distributed in the Glokhovskiy distribution.But the direction and magnitude of the deviation are related to the period and the wave height,especially whether the broken wave is fully propagated along the path.A constant near the slope size is added to the original Glokhovskiy distribution.The new Glokhovskiy distribution has been improved considerably compared to the original fitting effect.The wave nonlinear parameters of the normal,oblique and multidirectional waves on the slope are comparatively studied.The three parameters including with Ur,asymmetry A and skewness S are compared.On the whole,the influence of the incident direction on the nonlinear parameters is not obvious.