CFD Study On Flow Characteristics Around Bluff Body And Fluid-Structure Interaction Of Wind-induced Vibration

In this work, the flow characteristic around cross-section which is most commonly used in the civil engineering is simulated with the Shear-Stress Transport(SST) model and Large Eddy Simulation(LES) on the basis of current finite volume methods of CFD thesis. Beside, the wind-induced vibration has been simulated by using moving grid method. the main research work is as follows:1. The hydrodynamic characteristics of the circular cylinder which is commonly used in the civil engineering is simulated by computational fluid dynamic method with SST and LES turbulence model. The simulation is focused on three-dimensional flow characteristics and variation of drag coefficient,lift coefficient and Strouhal number with different Reynolds. The agreement of CFD simulation result with former recorded data prove the accuracy of two turbulence modle in bluff body calculation.This give a basis thesis for the further work of the paper.2. CFD technique is employed to obtain the mean wind pressure coefficient distribution at various heights of isolated large hyperbolic cooling tower. First, effects of surface roughness on mean pressure coefficient of concrete cooling tower which is below the high degree of code for cooling tower is tested. The comparison of CFD result with former recorded data via full-scale measurement and wind-tunnel testing shows that the effect of roughness on full-scale cooling tower surface can not be ignored.then, the method will be proposed to abtain the mean prssure coefficient of cooling tower with220meters heigh which is out of the high degree of standards. The mean pressure coefficient inside the cooling tower is discussed by a external program with heat and mass transfer, the result prove the correctness of external program,and provides a reference method for the determination of internal mean pressure coefficient of cooling tower. The effects of crosswind on the performance of cooling tower is discussed, and the principle of how to choice the defensive measures to crosswind is offered.3. A numerical method has been proposed to solving the fluid-structure interaction of vortex-induced vibrations and cross-wind galloping with the User Fortran module of ANSYS CFX. The simulation not only successfully captured the "lock-in" and "beat" phenomena,and reproduced the galloping which take place in the wind-tunnel. The results explain the formation mechanism of galloping well,and prove the correctness of method which can be used to the similar problems.4. By using the CFD numerical method as a platform, the moving grid technique is used to discussed wind effects on bridge, where the wind is induced by train.the result indicate that the variation trend of pressure which is induecd by train is similar under different condition with crosswind and without crosswind. The effects of shock wave by train with normal speed can be negligible in the design calculation of bridge. The effect of high speed train on the bridge is limited, while pressure shock wave may be dangerous to the subsidiary structure of bridge,and should be considered carefully.