| Flow around interference phenomena of cylinder clusters commonly exist in ocean engineering,such as the underwater columns of floating wind turbines in offshore wind farms,mooring facilities at island ports,and supporting columns of underwater tunnels.The flow around interference phenomena of cylinder clusters can affect the distribution of fluid mechanics characteristics in the flow field near the structures.In the face of extremely complex ocean environments,the mutual influence between cylinder clusters becomes more intense.This thesis aims to explore the characteristics of flow around interference of cylinder clusters,with the main goal of optimizing the arrangement of cylinders,reducing fluid resistance,and improving the safety of engineering structures,revealing the flow field interference mechanism of cylinder clusters under various arrangement forms.This thesis uses computational fluid dynamics(CFD)methods to construct cylinder clusters with different arrangement forms and motion characteristics to investigate the flow around interference phenomena of cylinder clusters at subcritical Reynolds number Re=3900,focusing on the analysis of single cylinder,double cylinder,and triple cylinder structures.First,a numerical tank model is established to study the flow around a single circular cylinder using numerical simulation,and the numerical results are compared with experimental results and literature results to determine the turbulence model and meshing method in the relevant numerical calculations.Secondly,based on the research foundation of a single circular cylinder,the flow characteristics of unequal diameter double circular cylinder,double square cylinder,and double triangular cylinder are studied,and the influence of different arrangement forms,cross-sectional shapes,and diameter ratios on the hydrodynamic coefficients of the cylinder and the shedding vortex structure in the wake are analyzed.Then,a flow around model of three circular cylinders arranged in a triangle is constructed,and numerical simulation studies under various operating conditions are carried out,analyzing the dynamic response characteristics and vortex shedding modes of cylinder clusters under different incident flow angles and spacing ratios,further clarifying the mutual interference effects of different cylinder clusters under uniform flow and the combined effects of wake flow from other cylinders,and revealing in detail the mechanical characteristic patterns and vortex shedding evolution trends of cylinder clusters with different arrangement forms in engineering phenomena.Finally,some typical flow characteristics are selected for the study of flow around a forced vibration cylinder,and the numerical simulation of cylinder motion under multiple operating conditions is conducted using overlapping mesh technology and custom motion equations.The numerical results show that parameters such as vibration frequency and amplitude have a strong influence on the flow characteristics,and there is a certain correlation between the abnormal changes of the lift coefficient of the cylinder cluster and the evolution of the vortex shedding structure.Through numerical simulation and result analysis of the flow around interference phenomena of cylinder clusters with different arrangement forms,this thesis reveals the flow field characteristics and force situation of cylinder clusters with different arrangement forms,which has important guiding significance for further research on flow around interference phenomena between cylinder clusters and the analysis of typical flow disturbance characteristics,and can optimize the design and construction of relevant structures in ocean engineering.Future research can be extended to three-dimensional flow around characteristics of cylinder clusters with more complex arrangement forms and operating conditions,to more accurately predict the hydrodynamic characteristics and wake interference of cylinder cluster structures. |
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