The present study aims to explore dynamical behavior of the fluid- elastic vibration of a single cylinder and three cylinders in shear flow by numerical simulations. This paper investigates the effects of the shear parameter, mass ratio, and spacing(P/D) on fluid-elastic vibration of the cylinders. Continuity equation and momentum equations are solved alternatively using a CFD package, Fluent 6.3.26. Dynamic meshing techniques together with the cylinder motion equations are employed in the simulation. Under different flow conditions, flow types, and cylinder motion models, lock-in and fluid-elastic vibration are studied. The results show that motion and flow types of a single cylinder in uniform flow are in agreement with the previous studies in literatures. In shear flow, however, as the shear parameter increases, the fluid-elastic vibration of the cylinder is induced, and thus amplitude of the cylinder increases considerably. Further, three cylinders in the shear flow are studied. Three cylinders arrangements (classified as side-by-side, tandem ,and stagger) and the distance between cylinders are the factors to cause fluid-elastic vibration. Compared with the single cylinder motion, three cylinders motion¡¦s critical flow velocity is smaller than that of the single cylinder motion, which means two cylinders motion are more subject to fluid-elastic vibration.

This research is aimed to investigate the fluid-elastic instability of the motion simulation using a single cylinder and two cylinders within the context of shear flows. T/D, shear parameter and mass ratio are parameters to be investigated. Besides, cylindrical motion treks and the amplitude are also analyzed. Continuity equation and momentum equations are solved alternatively using a CFD package, Fluent 6.3.26. The force caused by the flow interacts with the cylindrical motion. Thus Motion meshing techniques together with the cylindrical motion equations are employed in the simulation. Under different flow conditions, flow types and cylindrical motion models, lock-in and fluid-elastic instability are studied. The results show that motion and flow types of a single cylinder within the context of the uniform flow have a general agreement with the related literatures. In terms of the shear flow, however, as the shear parameter increases, the fluid-elastic instability is caused, and thus amplitude of the cylinder augments considerably. Further, double cylinders in the shear flow are studied. Double cylinder arrangements( classified as side-by-side and tandem) and the distance between cylinders are the factors to cause fluid-elastic instability. Compared with the single cylindrical motion, double cylindrical motion¡¦s critical flow velocity is smaller than the single cylindrical motion, which means double cylindrical motion are more subject to fluid-elastic instability.

The present study is aimed to explore dynamical behavior of the fluid- elastic vibration of cylindrical arrays and single cylinder in shear flow by numerical simulations .The effects of the shear parameter, spacing(P/D) ¡Bmass ratio and arrangement of cylinders on fluid-elastic vibration of the cylinders are investigated Continuity and momentum equations are solved alternatively by using a CFD package, Fluent 6.3.26. Dynamic meshing techniques together with the cylinder motion equations are employed in the simulation. Under different flow conditions, flow types and cylinder motion models, lock-in and vortex-induced vibration are studied. According to the research the motion and flow types of a single cylinder in uniform flow are in good agreement with the previous studies in literatures. In shear flow, however, as the shear parameter increases, the fluid vortex-induced vibration of the cylinder is induced, and thus amplitude of the cylinder increases considerably. Further, cylindrical arrays in the shear flow are studied. Cylindrical arrays arrangements (rectangle and rhombus) ¡B the distance between cylinders and regulate shear parameter are the factors to cause fluid-elastic vibration. Compared with the single cylinder motion, cylindrical arrays motion¡¦s critical flow velocity is smaller than the single cylinder motion, which means cylindrical arrays motion are more subject to fluid-elastic vibration.

The present study aims to explore dynamical behavior of the single cylinder and the staggered cylinder arrays in shear flow by numerical simulations. The results are compared with the case in uniform flow. After the observation of the fluid-elastic vibration in the staggered cylinder arrays in the two flows. This paper investigates the effects of the spacing(P/D), mass ratio and the shear parameter on the trajectories, oscillation amplitudes among the different cylinders. Continuity equation and momentum equations are used to solve the aforementioned problems alternatively by PISO method. Dynamic meshing techniques together with the cylinder motion equations are employed in the simulation. Under the different conditions, flow types and cylinder motion models, lock-in and fluid-elastic vibration are studied when the flow crosses the staggered cylinder arrays. The results show that the motion and the flow field around the single cylinder is consistent with the literature. In terms of the staggered cylinder arrays in uniform flow, the oscillation is dominated by the vortex shedding, and the lock-in area in the downstream cylinders is greater than the upstream cylinders. Fluid elastic vibration occurs in the small spacing between cylinders. In shear flow, when the shear parameters are larger or the spacing between cylinders are smaller, the more likely the fluid elastic vibration of the cylinders will occur.

The present study aims to explore dynamical behavior of the fluid-elastic instability of a circular cylinder in shear flow by numerical simulations. The theoretical model comprises two groups of transient conservation equations of mass and momentum and the governing equations are solved numerically with an iterative SIMPLEC(Semi-Implicit Method for Pressure-Linked Equations Consistent) algorithm to determine the flow property and to analysis structure stress simultaneously. Additionally, the TFI (Transfinite interpolation) computation procedure is applied to characterize the behavior of fluid-structure interaction. The predictions are in reasonable agreement with literature showing the validity of the present theoretical model. The numerical results indicate that there is a transverse force acting from high velocity side toward the low velocity side in shear flow. The magnitude of this transverse force increases with the shear parameter. The Strouhal number slightly increases as the shear parameter increases for all Reynolds number. As the pattern of the approach flow changes from the uniform to shear flow, the front stagnation point shifts to high velocity side, and the base pressure increase. The magnitude of the shift of front stagnation point is linear with the shear parameter. Furthermore, this study appraises the amplitude and orbit of fluid elastic vibration of a circular cylinder in shear flow, and shows the effects of the spring constant and damping factor on fluid elastic vibration of the cylinder. In addition, various effects including shear parameter and mass ratio on the critical velocity of the fluid elastic vibration also has been examined detail.

The present study aims to explore dynamical behavior of the fluid-elastic instability of a circular cylinder in shear flow by numerical simulations. The theoretical model comprises two groups of transient conservation equations of mass and momentum and the governing equations are solved numerically with Fluent software to determine the flow property. The analysis presented that there exist both vortex-induced vibration and flow-elastic vibration for single cylinder in sear flow. The numerical results with a Harmonic Model built from Gambit indicate that there is a transverse force acting from high velocity side toward the low velocity side in shear flow. The transverse force make cylinder move periodically and thus go to a vibration. Furthermore, this study appraises the amplitude and orbit of fluid elastic vibration of a circular cylinder in shear flow and shows the effects of the shear velocity slope and damping factor on fluid elastic vibration of the cylinder. Here in the thesis, as the function applied with Fluent of displaying dynamic mesh on-time, the movement and re-mesh of cylinder could be observed. A vibration expansion diagram was presented and the pictures of flow velocity and flow pressure were retrieved from Fluent.