| Summary: | 博士 === 中原大學 === 機械工程研究所 === 98 === Abstract
In this thesis, a long bubble elongates through a contraction tube followed by an expansion tube filled with viscoplastic fluids was studied experimentally and numerically. The effects of both tube geometry and fluid characteristics on the bubble profiles and fractional converge were evaluated.
In the experimental aspect, the bubble profiles and the fractional converge were obtained by image processing the photos captured with a high-speed camera. In the numerical analysis aspect, the continuity equation and momentum equation were converted to the equations in the form of streamline and vorticity. The differential equations were discretized with the finite difference method. Gauss-Seidel Iteration method with successive over-relaxation (SOR) were applied in the computation of the viscous fluid flows. The evolution of the bubble contour predicted by a conservative Level Set Method was applied to this study.
The results showed that the fractional converge of the fluid, the bubble profile and velocity changed due to the effects of the fluid viscosity, the flow rate and the contraction/ expansion angle of the tube. The bubble profile, developing along the stream line, was changed by the effects of the inertia force, surface tension and capillary force. The bubble profiles and the flow fields generated by numerical simulation were applied to explain the experimental observations. Both experimental observation and numerical simulation results were in the same trend. A good consistency was shown between our results and the related researches.
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