Breakup of a pendant magnetic drop

Nicolas Havard (1, 2) , Frederic Risso (1) , Philippe Tordjeman (1)

1 IMFT - Institut de mécanique des fluides de Toulouse
2 ENS de Lyon - École normale supérieure de Lyon

We report experiments on a millimeter-sized pendant drop of ferrofluid in a horizontal magnetic field. The initial drop size is chosen just below the breakup threshold under gravity. As the magnetic field is increased, the drop tilts in order to align with the direction of the total volume force that is exerted on it: weight plus magnetic force. The breakup is controlled by a generalized Bond number based on this total force and on the radius of the neck of the drop. The evolution of drop shape turns out to be a complex process governed by many parameters such as the angle between the total force and the needle, the drop size relative to the needle radius, and the wettability of the liquid on the needle material. This suggests a certain universality, that a single value of the critical Bond number is found regardless of magnetic fluid properties and whether the force is inclined or not.

Mots clés: Magnetism; Pendant magnetic drop; Magnetic fluid properties

Domaines: Mécanique des fluides [physics.class-ph]; Mécanique des fluides [physics.class-ph]

Nicolas Havard, Frederic Risso, Philippe Tordjeman. Breakup of a pendant magnetic drop. Physical Review E : Statistical, Nonlinear, and Soft Matter Physics, 2013, vol. 88, pp. 1-5. ⟨10.1103/PhysRevE.88.013014⟩. ⟨hal-00904894⟩