Numerical Simulation And Analysis Of Internal Solitary Wave Propagation On A Slope Topography

With the rapid development of economy,land resources are exhausted day by day,and the ocean has become the most important part of the development of oil and gas resources.The South China Sea area is rich in oil and gas resources,which has become the main area of marine oil and gas development in China.In the South China Sea,due to the complex topography,the stratification characteristics of water body are obvious,and the internal isolated waves are common.The internal isolated wave is often large amplitude,strong carrying energy and long duration.Sudden strong current will be induced during the propagation process,and the drilling platform will move greatly when it is serious,so it is a great threat to the offshore engineering structure.This paper studies the deformation and flow field changes of the internal isolated wave in the process of slope terrain propagation,which can provide important reference for the structural design and layout of offshore platform and oil and gas pipeline,and has a strong engineering application value.Based on the N-S equation and Kd V series internal solitary wave theory model,the velocity inlet wave making method,artificial damping plus numerical dissipation wave elimination method and VOF method are used to capture the internal interface.The two-layer numerical water tank of isolated wave in the fluid is constructed by the secondary development of commercial software star-ccm+.The results show that compared with the two methods of only given stratified fluid velocity or the specified fluid velocity and monitoring boundary water level,the measured wave simulated by the method of volume fraction is more consistent with the theoretical waveform,The amplitude is closer to the target amplitude,and is limited by the limit amplitude of the internal isolated wave theory,and the amplitude range can be applied more widely.Based on this velocity entry method,the wave amplitude can be controlled by fitting the numerical experimental results.The numerical simulation results show that the numerical flume established in this paper is accurate and applicable to the study of the interaction between isolated waves and topography.The numerical sink of isolated waves in large amplitude is established,and the propagation of isolated waves in the absence of terrain is simulated,and the flow field structure of the internal isolated wave is analyzed.The results show that the measured wave is in agreement with each other under different amplitude,and the applicable amplitude range of each kind of internal isolated wave theory model is determined.The wave surface and flow field characteristics of the internal solitary wave propagating on different slopes are studied by using the parameters of the internal isolated waves observed in the Liuhua sea area of the South China Sea.The results show that the first half wave gradually slows and the second half wave becomes steeper,the horizontal velocity of upper fluid decreases and the horizontal velocity of lower layer increases during the interaction between internal isolated wave and slope.When the ratio of the amplitude of incident wave to the depth of the lower layer of the slope is less than0.5,the internal isolated wave does not break,and the crest wave peak appears when the climbing is completed.The horizontal velocity near the bottom reaches the maximum,which can reach 1.5-2.5 times of the speed before climbing.When the ratio of incident wave amplitude to the depth of the lower layer of slope is greater than 0.5,the interaction between the internal isolated wave and slope will break.The larger the slope is,the earlier the crushing position is,the greater the breaking strength is,the greater the mixing area of fluid is;The horizontal velocity of the near bottom surface reaches the maximum after the slope is broken,which can reach 1.7-2.8 times before the slope action.