On the Reynolds Number of an Abruptly-stopped Free Falling Circular Cylinder in Transitional Stage
| Autor: | 林宏彥 |
|---|---|
| Rok vydání: | 2015 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 103 Flow passed cylinder structure is a classical and complicate problem of fluid mechanics, besides it is important in engineer applications. This study simulated an abruptly-stopped free falling cylinder at different Reynolds numbers using two-dimensional Navier-Stokes equations. The cylinder motion characteristics and the flow characteristics varied with time. To observe, the cylinder was designed to stop at six abruptly-stopped times in a pseudo-period. Furthermore, the process of free falling cylinder at different Reynolds number was discussed by analyzing the parameters: Lift, Drag, Vibration frequency and Amplitude, etc. Then the flow field and motion characteristics of free falling cylinder were discussed. The process of free falling cylinder motion could be divided into three stages in sequence, i.e. Initial, Transitional and Mature stages. This study focused on the Transition stage. The flow kept going forward and produced a large force on the cylinder after the circular cylinder was abruptly-stopped. There were vortices behind the cylinder in the process of free falling cylinder. When the cylinder was abruptly-stopped,the reversed vortices were produced because of the blocking effect of the cylinder. With the increasing of Reynolds number, the flow speeded up, the vortices moved faster, and the track of vortices might curve backward. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
| Externí odkaz: |
|