Study On Flow Field And Response Characteristics Of Internal Solitary Wave Interacting With Floating Structure

The internal wave is a kind of ocean hydrodynamic phenomenon that frequently occurs in layered water.Because of its large amplitude and strongly associated shear flow,it is one of the important threats to marine engineering.Internal solitary waves,as the main form of ocean internal waves,show a strong nonlinear process.In the South China Sea,there are frequent occurrences of internal solitary waves.Large-scale internal solitary waves have also been found in the Yellow Sea and the Bohai Sea.In order to fully evaluate the threat of internal solitary waves and ensure the safety of the operation of floating structures,it is of great significance to clarify the interaction mechanism of internal solitary waves and floating structures,and to explore the response mechanism of floating structures under the action of internal solitary waves.This paper relies on the computational fluid dynamics software Fluent to establish a laboratory-scale layered fluid numerical water tank,and uses the gravity collapse method to achieve the simulation generation of internal solitary waves.In order to ensure the reliability of the numerical model,the numerical wave-forming results were compared with the physical model experiments.Based on the established two-dimensional numerical flume,the interaction process of internal solitary waves with typical fixed floating structures and free-moving floating structures was studied respectively.Aiming at three typical fixed floating structures,rectangular,arch and bilge arc rectangular,the wave parameters,flow field patterns and forces changes of the structure before and after the solitary waves in different amplitudes pass through the structure are studied.The results show that internal solitary waves will undergo different degrees of amplitude attenuation and waveform deformation after passing through the structure.Before propagating to the structure and leaving the structure,large vorticity values will be formed in the front and back of the structure,respectively,and the flow field will also change relatively,especially the flow field structure at large amplitude will affect the structure force process.For the free-moving floating structure,the cross-sectional structure of "HAI YANG SHI YOU 117",the first floating production storage tank(FPSO)designed and built in China,is used as the scale ratio model,using dynamic grid technology The response mechanism of two structures,rectangular and bilge arc rectangular,under the action of internal solitary waves isanalyzed.The results show that when the rectangular cross-section structure encounters internal solitary waves in the lateral direction,the sway motion changes greatly and the sway motion changes little.Whether the bilge is arc-shaped can affect the rolling mechanism of the rectangular cross-section and the changing process of the velocity field.In this paper,the research on the evolution characteristics of internal solitary waves before and after passing through floating structures has important theoretical and engineering significance for predicting the motion response of floating structures under the action of internal solitary waves.