Coaxial liquid-liquid flows were numerically studied in a nesting two-tube system. Calculations were carried out when various exit-lengths (meaning length differences between the two tubes) were used. Numerical result...Coaxial liquid-liquid flows were numerically studied in a nesting two-tube system. Calculations were carried out when various exit-lengths (meaning length differences between the two tubes) were used. Numerical results indicated that there exists a certain range of exit-length for the liquid-liquid flows to form stable and smooth interfaces, which requires that the exit-length should roughly be less than 5.6 times the outer tube diameter. In this range, interface instability is effectively restrained and the core fluid shows a phenomenon of die swell. When the exit-length is about 1.6 times the outer tube diameter, the core fluid has the greatest diameter size in the shell fluid. Velocity distributions at the outer tube exit favor formation of a continuous and stable core-shell structure.展开更多
基金Project supported by the National Natural Science Foundations of China (No. 10402031) and the NanoSci Tech Promotion Center, theShanghai Science & Tech. Committee (No. 0352nm091), China
文摘Coaxial liquid-liquid flows were numerically studied in a nesting two-tube system. Calculations were carried out when various exit-lengths (meaning length differences between the two tubes) were used. Numerical results indicated that there exists a certain range of exit-length for the liquid-liquid flows to form stable and smooth interfaces, which requires that the exit-length should roughly be less than 5.6 times the outer tube diameter. In this range, interface instability is effectively restrained and the core fluid shows a phenomenon of die swell. When the exit-length is about 1.6 times the outer tube diameter, the core fluid has the greatest diameter size in the shell fluid. Velocity distributions at the outer tube exit favor formation of a continuous and stable core-shell structure.
文摘以现场实测道路交通数据为基础,对VISSIM微观仿真模型进行标定及有效性检验,分析了出口通行能力的影响因素.以出口速度及流量为评价指标,研究了不同交通流量组合情况下附加车道长度的变化规律.结果表明,附加车道长度与辅路及出口流量大小有关,出口附加车道合理长度为100~120 m,条件受限时取100 m.
