Analysis On The Characteristic Of The Bubble Entrained By The Plunging Wave

There are amounts of tiny bubbles in the surface of the ocean.These bubbles are mainly generated by the breaking wave.Breaking waves cause strong turbulence and curling,entraining substantial air into water to form air bubbles.The sediment and pollutant transports in the surf zone are affected by evolution and transport of the bubbles.What’s more,in terms of the interaction between the ocean and atomosphere,the break of bubbles on the ocean,not only can increase the contact area and energy conversion rate between the ocean surface ande atomosphere,but also release the gas and vapor inside the bubbles.lt has an indirect influence on the heat balance between the ocean and atomosphere.The most common wave breaking generated near the coastal area.Consequently,it is of great theoretical and practical significance for the mechanism of two-phase flow to study the characteristics of the bubbles in the nearshore surf zone.And the study are expected to serve for coastal engineering constructions and coastal researches.There is an experiments were performed to investigate the characteristics of bubbles generated by the plunging waves,which was based on a 2D wave flume,combined with a mathematical analysis.The reasearch depth was 0.3 m,0.3 5 m,and 0.4 m,wave height was 0.05 m,0.08 m and 0.1 m,and the beach slope was 1:10.This paper is mainly about the plunging wave.The first part is the study of bubble distribution and population in the surf zone.The second part is the analysis of the void fraction in the surf zone.The third part is the analysis of the evolution of the entrained by the plunging wave in the surf zone.The main results as follows:(1)There is a significant exponential relationship between the chord and the probability density of the bubble in the surf zone under the plunging wave.The bubble probability density is exponentially decay with the increase of the bubble size.The Hinze scale of the bubbles for this experiment is about 4mm,the bubble particle size distribution according to different distribution rules,and the boundary is the Hinze scale;(2)With the increase of the depth,the index a decreased.The closer to the "bubble generation area",the more small bubbles occured,and the larger bubbles usually appear far from the "bubble generation area" where the volume of the water is more intense.The wave height has a great influence on the bubble size distribution and the bubble population.While the impact of water depth is not obvious;(3)Under the plunging wave,the void fraction show a expotential decay with the depth increased.The closer to the "bubble generation area",the stronger water turbulance generated,and form the larger void fraction.And there is an expression of the vertical distribution of void fraction in the surf zone,which is obtained by fitting the experimental data;(4)The established mathematical model were used to analyze the flow fied and the turbulence energy,and analyze the evolution of the air entrained by the plunging wave in detail.The mathematical results are consistent with the experiment results,which prove the reliability of the mathematical model established in this article.