The Numerical Simulation Of The Interaction Of Internal Solitary Waves With The Deep-sea Semi Submersible Platform And Riser

The marine structures will suffer from much extreme oceanenvironments in deep-seas, one of them is the internal solitary wave. Suchan ISW has significant influence on the safty of marine structures due toits characteritics of the large amplitude and long lastig time.Content results can hardly be attained by normal linear potentialtheory since the interaction between the internal solitary wave and themarine structure is a much complicated problem due to its great nonlinearcharacteristics. Therefore, the numerical flume method will be aneffective and direct way for solving this problem.On the basis of reviewing and summarizing recent progress of theproblem, the works in the thesis are presented as follow:In chapterⅡ, based on the Reynolds-Averaged Navier-Stokes(RANS) equations closed by employing the k ?εmodel and the volume offluid (VOF) method tracking a moving interface in a two-layer fluid, anumerical internal-soliton flume was developed by use of the double-piston wave-maker method and the wave absorbing technology based theporous mediums with multiple layers, the validity of generating andabsorbing waves for such a numerical flume has been confirmed.In chapterⅢ, the interaction between the internal solitary wave andthe GVA7500 semi-submersible platform was numerically simulated andanalyzed by use of the proposed numerical flume. The characteritics ofthe sudden impact loads and surface pressure distibution on the semi-submersible platform due to such an internal solitary wave werepresented and discussed.In chapterⅣ, the interaction between the internal solitary wave andsome deep-sea riser with the high aspect ratio was numerically simulated and analyzed by use of the proposed numerical flume and the finiteelement method based on the thin shell model. The characteritics of theexternal dynamic loads and surface pressure distibution on the deep-seariser due to such an internal sloitary wave were presented and the effect ofthe internal solitary wave on the dynamic responese for such a seep-seariser was discussed.