Experimental And Numerical Studies On Run-up Of Multi-solitary Waves On Slope

Propagation of a silitary wave and interaction between two solitary waves,including head-on collision and overtaking,belong to a well invesitgated classic field of water wave mechanics and applied mathematics.It was reported recently,through field data analysis and numerical simulation,that different wave profiles of tsunamis could appear after propagating from deep see to shalllow region over a wide contenetial shelf.Undular bores and a wave train of several solitary type waves are the typical wave profiles.Studies on physical moelling and numerical simulation of the genration,propagation and runup of a wave tarin of several solitary type waves are not only of special interests for extending the solitary wave theory,but also of important applications in researching into the mechanism of tsunami harzards in coastal regions and evaluating the tsunami loads on coastal structures.Firstly,the triple solitary wave,which is defined as a wave train of three solitary waves with the same,are generated amplitude in a wave flume by using a piston-type wavemaker and the modified Goring’s wave-generating method.The experiments of the run-up of the wave train constituted by several solitary waves on a plane beach of 1:10 slope are conducted.The time series of the surface elevation are measured by the wave gauges installed along the wave flume and the movement of the waterline on the beach is recorded by two high speed cameras.The effects of the relative wave amplitude of the target solitary wave and the dimensionless distance between two successive wave crests on the run-up amplifications of individual waves are analyzed and discussed.Then,numerical simulations of wave run-up on a slope are implemented by using Flow-3D CFD software.The RANS equations,RNG k-turbulence model and VOF method are adopted in the numerical simulations.The results of experiments and numerical simulation turn out that the influence of the leading solitary wave on the run-up of the following one is significant due to the wash down flow and the resulting breaking of the following wave induced by the leading wave.The run-up coefficients of the following solitary waves are smaller than that of the leading solitary wave while the run-up amplification coefficient of the third wave is greater than that of the second wave.The type of wave breaking relates to the crest distance of incoming solitary waves.This variation of the run-up coefficients of individuals in the successive solitary wave train becomes more significant as increasing the initial relative wave amplitude and the crest distance of incoming solitary waves.