Analytical Study Of Internal Wave Evolution Mechanism Under Fluid Stratification Conditions

Internal wave is a very common marine phenomenon,which often occurs in water with different densities.Due to the huge vertical shear force and strong current during the propagation of internal wave,it can threaten the navigation safety of naval ships,damage marine structures and even cause heavy loss of personnel and property.Therefore,the study of internal wave is a very important and meaningful work.An internal wave model is an effective way to describe internal waves.It can be divided into rigid cover hypothesis and free surface hypothesis according to the motion of the upper surface.Firstly,the internal wave equation with terrain at the bottom is established according to potential flow theory.Then the analytical solutions of velocity function and wave surface function are solved and the model is verified by experiment.The research content is divided into the following two aspects:Firstly,the article establishes internal wave models of rectangular terrain conditions,rigid surface and free surface with three layers of fluid stratification.The solution region is divided according to the characteristics of the bottom terrain and the velocity potential function and the wave surface function are solved by the method of perturbation expansion.The properties of their analytical solutions are explored and the similarities and differences between the two models are compared.Secondly,the article verifies the rigid surface and free surface.For the rigid surface model,the internal wave curve is obtained by physical experiment and compared with the theoretical curve to verify the coincidence degree.For the free surface model,the wavefront duration curves at different positions are obtained by numerical experiments,and the experimental curves are compared with the theoretical curves to verify the reliability of the model.