Experimental simulation and analysis of irregular sea wave groups

Based on the improved empirical wave envelope spectrum,a method to simulate unidirectional irregular wave groups was developed in this paper.Simulation examples demonstrated that irregular wave groups which included not only its group height but also its length could be conveniently simulated by this empirical wave envelope spectrum,the wave parameters and the parameters for the description of the wave group height and group length were given.Then,the calculation method of the wave maker signals for generating irregular wave groups at a specified position in the wave flume was proposed.Random waves containing expected wave groupiness and wave spectrum were satisfactorily simulated in the laboratory.In addition,the variation of the wave groupiness with the wave propagation was investigated.It shows that the waves with desired wave groupiness should be generated at a specified position in the wave flume for physical model test considering the wave groupiness,which is different from the experiments on the common random waves.