| Summary: | 碩士 === 國立成功大學 === 水利及海洋工程學系碩博士班 === 93 === Because of the interaction of separation and multiple vortices between two circular cylinders, the flow through two aligned circular cylinders is more complex then that of a single one. This study attempts to resolve this complex flow field using the commercial software, FLUENT, since it accommodates the completely module of the Reynolds stress model (RSM) for three-dimensional turbulent flow computation. The distance to diameter ratio of the cylinder, and the Reynolds number based on approach velocity and D are the two main parameters that are concerned in the computations.
The model constructed is verified by the experimental data from visualization techniques and the model is then used to simulate flows at Reynolds numbers of 1000 and 5000 and various ratios. The horseshoe vortex, up flow and wake flow existed between two circular cylinders can be simulated clearly at those Reynolds numbers and ratios.
Computed results show that the flows through the aligned circular cylinders are the combinations of the wake flows, the vortex near the water surface and the horseshoe vortex rising from the bottom. The flow features show differently for ratios at 2, 3 and 4, 5. For the flows of the 2 and 3 ratios’, the wake flow generated from the front cylinder interfere with that at the behind, while the distance of the 4, 5 ratios is sufficient that the interferences are lesser than the 2, 3 cases. In addition to these results, the experience gained from the setting up of the computational model using FLUENT can also be a reference for other applications.
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