Experimental Study On Interactions Between Water Waves And Shear Flows Using DPIV

Wave-current interaction is a non-linear frontier issue,and it's also one of the most important problems in ocean engineering.At present,there are many theoretical and simulated experiments on wave-current interaction.However,most of the existing researches are limited to some basic assumptions,and there are still many shortcomings in the study of nonlinear wave and shear flow.In this paper,the method of physical model experiment is used to simulate the regular wave,focused wave and their evolution in uniform flow and shear flow.The main characteristics of wave and hydrodynamic characteristics are studied.The flow and wave flow field are analyzed based on DPIV(Digital Particle Image Velocimetry).The aim of this paper is,On the one hand,to study the nonlinear characteristics and the action of wave current under the complex flows field.On the other hand,to provide a real basis for exploring the complex mechanism of wave-flow interaction.In this paper,the physical model is introduced in detail,and the layout,DPIV technique,wave generation method and experimental element,different profile flows are systematically described.Then we briefly describe the high-order wave theory method and the focusing wave mechanism used in this paper.Then,the following results are obtained by analyzing the wave-flow interaction tests under different currents.In the hydrostatic test,the wave characteristics and the wave flow field are analyzed emphatically.It shows that the fifth order Stokes wave theory can describe the influence of nonlinearity well.Then,on the basis of this,we test the focusing waves.In this paper,we find a best theoretical method to describe the wave field of the focusing waveBased on the high-order wave theory,the Doppler principle is used to analyze the variations of wave height and flow field in the uniform current.It is proved that the Doppler-shift solution describe the interaction of uniform current and regular waves well.Then the analysis of the vorticity in the shear flow field is carried out.It is found that the vorticity distribution has a significant effect on the wave height and the wave asymmetry.In the analysis of contrast shear flow and uniform flow wave variation,the comparison between the theoretical model and the measured data shows that the vorticity has a significant change in the dispersion relation,which affects the wave characteristics and the flow field characteristics.In the experiment of focusing wave in different flow fields,the characteristics of focusing wave in uniform flow field are described based on Doppler principle.It is proved that the method of focusing wave in hydrostatic condition is suitable for uniform flow condition.And then compare the change of the limit wave height under different water flow conditions,which indicates that the forward vorticity has an important effect on the increase of the limit wave height.At the same time observe the broken waves,accurately provide the broken wave characteristics and flow characteristics.