Experimental Study On The Characteristics Of Breaking Waves Based On Three-dimensional Wave Energy Focusing

Wave breaking is a basic phenomenon,which plays an important role in wave growth,wave-body interaction and the exchange of seawater and atmosphere.Since the propagation of waves is multi-directional in the actual sea state,especially in deep water,the multi-directional wave breaking is quite different from the near-shore wave breaking,which is still not fully understood at present.In order to further understand the characteristics of the multi-directional wave breaking,a three-dimensional multi-directional breaking wave experiment was carried out in the present study.Based on the method of three-dimensional wave energy focusing,the present study simulate the generation of non-breaking waves and breaking waves in a three-dimensional wave basin.Two forms of the spectrum distribution,multi-directional single-frequency spectrum and multi-directional multi-frequency spectrum,are employed.For each form of spectrum,the present study investigated the parameters,including the distribution of wave height,the characteristic of the free surface,the geometric parameters of breaking waves and the energy loss,by increasing the focusing wave height to increasing the intensity of waves.The effect of wave directional distribution on wave-breaking parameters was analyzed.The results show can be summarized as follows: 1.The directional distribution has a significant effect on wave propagation and wave breaking.Compared to the wider directional distribution,the wave-breaking parameters will be larger,the waves are less likely to break and the larger non-breaking waves will be generated in a narrow directional distribution.2.The energy loss is affected by the width of the directional distribution when wave is breaking.For the multi-directional single-frequency waves,when the directional distribution is wide,the energy loss will be great due to the wave breaking.When the directional distribution ?max=60°,the maximum energy loss rate is approximately 45%.For the multi-directional multi-frequency waves,when the directional distribution ?max=30°,the maximum energy loss rate is approximately 35%.3.The geometric parameters are obviously affected by wave parameters,and its range varies greatly.Therefore,it is not suitable to be used as the index to distinguish wave breaking.4.The propagating direction of the multi-directional single-frequency waves will change to a certain extent during the propagation of the waves,and the waves on both sides will be concentrated in the main direction,especially for the case with wider directional distribution.However,it is not obvious for the multi-directional multi-frequency waves.The results of the present study will throw light on the three-dimensional wave breaking in the actual deep sea,and can be used as a reference for numerical simulation.