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Shear velocity criterion for incipient motion of sediment 被引量:1
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作者 Francisco J.M.SIMOES 《Water Science and Engineering》 EI CAS CSCD 2014年第2期183-193,共11页
The prediction of incipient motion has had great importance to the theory of sediment transport. The most commonly used methods are based on the concept of critical shear stress and employ an approach similar, or iden... The prediction of incipient motion has had great importance to the theory of sediment transport. The most commonly used methods are based on the concept of critical shear stress and employ an approach similar, or identical, to the Shields diagram. An alternative method that uses the movability number, defined as the ratio of the shear velocity to the particle's settling velocity, was employed in this study. A large amount of experimental data were used to develop an empirical incipient motion criterion based on the movability number. It is shown that this approach can provide a simple and accurate method of computing the threshold condition for sediment motion. 展开更多
关键词 incipient motion sediment transport Shields diagram critical shear stress criticalshear velocity movability number
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不同剪切条件下酚醛树脂冻胶动态成胶研究 被引量:3
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作者 史胜龙 王业飞 +3 位作者 姜维东 张健 于海洋 吕鹏 《中国海上油气》 CAS CSCD 北大核心 2013年第3期39-43,共5页
实验研究了酚醛树脂冻胶在搅拌剪切和振荡剪切条件下的动态成胶过程、动态成胶时间、临界成胶剪切速率及剪切对剪切后静置成胶粘度的影响,结果表明:不同剪切条件下酚醛树脂冻胶体系交联反应过程均经历了诱导、成胶、稳定、下降等4个阶段... 实验研究了酚醛树脂冻胶在搅拌剪切和振荡剪切条件下的动态成胶过程、动态成胶时间、临界成胶剪切速率及剪切对剪切后静置成胶粘度的影响,结果表明:不同剪切条件下酚醛树脂冻胶体系交联反应过程均经历了诱导、成胶、稳定、下降等4个阶段,与静态成胶相比多了下降阶段,并且相同配方的冻胶体系搅拌剪切作用强于振荡剪切;随着聚合物和交联剂用量增大,冻胶体系初始成胶时间和最终成胶时间均缩短,与静态成胶相比,冻胶体系初始成胶时间在低剪切速率下缩短,而在高剪切速率下延长;相同配方的冻胶体系在搅拌剪切下的临界成胶剪切速率小于其在振荡剪切下的临界成胶剪切速率;在诱导阶段剪切对静置后冻胶体系粘度没有影响,因此在现场注冻胶过程中注入时间应控制在诱导阶段之前。 展开更多
关键词 酚醛树脂冻胶搅拌剪切振荡剪切动态成胶 临界成胶剪切速率
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