Jiang Xiao F, Li Huai Z
Laboratory of Reactions and Process Engineering, CNRS, Université de Lorraine, 1, rue Grandville, Boîte Postale 20451, 54001 Nancy cedex, France.
Phys Rev E Stat Nonlin Soft Matter Phys. 2015 Dec;92(6):061003. doi: 10.1103/PhysRevE.92.061003. Epub 2015 Dec 30.
The pinch off of heterogeneous ferrofluid drops at a nozzle in air was experimentally investigated with a magnetic field (downward or upward) and without a magnetic field. Compared to homogeneous drops, the self-similarity and universal scaling law were verified through modifying the initial conditions, such as the nozzle diameter, flow rate, and magnitude and direction of the magnetic fields. Two pinch-off points were observed, and the two consecutive pinch-off dynamics were characterized through scaling laws. Here our scaling exponent remains within the scope of (0.70-0.80) for the primary whereas it remains within the scope of (0.60-0.70) for the secondary pinch off, respectively, comparable to the classic range from 2/3 to 1 for homogeneous drops. The gravity-compensating and gravity-superimposing magnetic fields display a negligible effect on the exponent but determine the sequence of double pinch offs. The universal character of the self-similar pinch off is extended to a heterogeneous fluid.
在有磁场（向下或向上）和无磁场的情况下，对空气中喷嘴处非均匀铁磁流体液滴的 pinch off 进行了实验研究。与均匀液滴相比，通过改变初始条件，如喷嘴直径、流速以及磁场的大小和方向，验证了自相似性和通用缩放定律。观察到了两个 pinch-off 点，并通过缩放定律对两个连续的 pinch-off 动力学进行了表征。在这里，我们的缩放指数对于主 pinch-off 分别保持在（0.70 - 0.80）范围内，而对于次 pinch-off 则保持在（0.60 - 0.70）范围内，与均匀液滴的经典范围 2/3 到 1 相当。重力补偿磁场和重力叠加磁场对指数的影响可忽略不计，但决定了双 pinch-off 的顺序。自相似 pinch-off 的普遍特性扩展到了非均匀流体。
