| As the population increases year by year and land resources are overexploited,the future development of society will depend more and more on marine resources.Non-renewable energy sources such as oil and natural gas will more and more rely on the rational exploitation and utilization of marine resources.Since the 21st century,China's comprehensive strength has developed rapidly.In order to adapt to the development requirements of the times,the study of marine engineering is particularly important.The scope of marine engineering research includes all projects involving or related to the marine environment,such as offshore oil platforms,marine oil pipelines,etc.As the main body of underwater oil pipeline and one of the important components of offshore oil platform,horizontal cylinder has very important research significance.This paper studies the numerical simulation analysis of horizontal columns under the action of waves,which is intended to coordinate the interaction between horizontal cylindrical structures and waves in marine engineering structures and is conducive to the construction of marine engineering.The content of this paper is divided into two parts:the numerical simulation of horizontal fixed cylinder under wave action and the numerical simulation of suspended horizontal cylinder in vertical free motion.The model of VOF(volume of fluid)is used to simulate the numerical simulation environment of the water-gas two phase flow,and the k-?turbulence model is used to simulate the required environment.To ensure that the combination of models is feasible,the simulated result in this paper is compared with the experimental results under the similar environment of the Keulegan-Carpenter number(abbreviated as the KC number),which means,the KC number ranges from 1.57 to 3.14,and the Re number is about10~5.Three conditions of the wave(level three,level four,and level five)and three conditions of cylindrical sizes(1 times,1.5 times,and 2 times the wave height)were simulated.At three conditions of the underwater depths(2 times,2.5 times,and 3times the wave height),the force of a horizontally fixed cylinder is analyzed,and a detailed analysis of the flow field around the cylinder is carried out.For the freely horizontally floating in the vertical direction column,three conditions of the wave(level three,level four,and level five)and three conditions of densities of the cylinder(600 kg/m~3,700 kg/m~3,800 kg/m~3)are used for the analysis of the movement and force.For the interaction between the fixed horizontal cylinder and the waves,this paper analyzes the impact of the cylindrical size,the depth of immersion and the wave parameters.Since the structure in the fluid occupies part of the flow channel,the overflow area is reduced,and the structure has a blocking effect on the flow.The size of the C_D and C_L is positively correlated with the size of the cylinder and not affected by the immersion depth of the cylinder.The theoretical derivation shows that the size of C_L is proportional to r/v~2.For the numerical simulation of the interaction between horizontal columns floating in vertical direction and waves,the factors affecting the force of the cylinder are mainly wave steep parameters and density of the cylinder.As the density of the cylinder increases,the phenomenon of the waves turning over the horizontal cylinder structure presents.Thus C_D and C_L are positively related to the cylinder density.In the case where the wave overturns the horizontal cylindrical structure,the increase in the wave steep parameter and the movement of the cylinder in the vertical direction gradually increase the degree of wave fragmentation.Therefore,C_D and C_L are negatively related to the wave steep parameters.In terms of cylinder motion,the main influencing factor of cylinder vibration amplitude is the wave steep parameter,and the main influencing factor of cylinder vibration center position is cylinder density.And with the change of cylinder density,its movement law changes. |
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