title: Self-similar pinch-off mechanism and scaling of ferrofluid drops.
abstract: 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.
authors.affiliation: Laboratory of Reactions and Process Engineering, CNRS, Université de Lorraine, 1, rue Grandville, Boîte Postale 20451, 54001 Nancy cedex, France.
authors.forename: Xiao F
authors.initials: XF
authors.lastname: Jiang
authors.affiliation: Laboratory of Reactions and Process Engineering, CNRS, Université de Lorraine, 1, rue Grandville, Boîte Postale 20451, 54001 Nancy cedex, France.
authors.forename: Huai Z
authors.initials: HZ
authors.lastname: Li