Analysis Of Force Of Flow Around Single Column Of Sea-crossing Bridge

There is an interaction between the middle and lower structures of the bridge and the flow of water.Because of the diversity in the lower structure of the bridge,the analysis of this effect is very complex and is still being explored.In order to study the basic law of this effect,this paper is to simulate and analyze the flow around a single column of the basic member of the bridge substructure.At present,the study on the high Reynolds number of the three sections of circular,square and circular end single column is still not sufficient,and many of the smaller structures and fluids are air flow.Moreover,many tests under high Reynolds number are also carried out in wind tunnel.Therefore,the flow analysis of pure flow in a single column with three Reynolds numbers is carried out in this paper,and the feasibility of the scale experiment is discussed.First,the theory of flow around numerical simulation is explained,and the selected model dimensions,mesh,algorithm and turbulence model are introduced.Then the grid independence verification is carried out,and then the 2D and 3D flow around the cylinder in Re=2×10~6 and Re=8×10~6are simulated by this discrete method,and the calculation results of different dimensions and Reynolds numbers are compared and analyzed.Then,the 2D and 3D numerical simulation of the column and round end column under Re=2×10~6 were carried out respectively,and the calculation results of different dimensions in different sections were compared and analyzed.Finally,taking single cylinder as the prototype in the Re=8×10~6 working condition,the numerical simulation of single cylinder under different scale ratio conditions is carried out.The calculation results are converted to the prototype according to the similarity criterion of Froude,and the theoretical feasibility of each scale ratio model test is analyzed and compared.According to the analysis and comparison of the numerical simulation results,it is believed that the numerical simulation of single column flow must be 3D under the finite depth of water,and the 2D simulation is only suitable for the case of infinite depth or in deeper water,while the square column and the circular end section require deeper water depth.The resistance coefficient(C_d)and the lift coefficient(C_l)oscillation frequency of the 3D simulation are not strictly 2 times,and smaller than the 2D simulation results;and because the rise resistance is the resultant force on the whole column,the 3D simulation results of high Reynolds number are difficult to have 2D regularity and stability.The water effect of square column resistance is obviously larger than that of the cylinder under the same condition.The flow force of the scale model can not be reduced to the prototype pier column according to the Froude similarity criterion.The flow force of the prototype pier can only be calculated by the Morison equation.