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Accueil > Productions scientifiques > Faits marquants > 2016 > Langmuir - 2016 : Static Magnetowetting of Ferrofluid Drops

Langmuir - 2016 : Static Magnetowetting of Ferrofluid Drops

par Ali Abou-Hassan - 1er juillet 2016

Static Magnetowetting of Ferrofluid Drops
Langmuir, 2016, DOI:10.1021/acs.langmuir.6b01934

by : Carlo Rigoni, Matteo Pierno, Giampaolo Mistura, Delphine Talbot, René Massart, Jean-Claude Bacri, and Ali Abou-Hassan

Contact PHENIX

Abstract :

We report results of a comprehensive study of the wetting
properties of sessile drops of ferrofluid water solutions at various
concentrations deposited on flat substrates and subjected to the action of
permanent magnets of different sizes and strengths. The amplitude and
the gradient of the magnetic field experienced by the ferrofluid are
changed by varying the magnets and their distance to the surface.
Magnetic forces up to 100 times the gravitational one and magnetic
gradients up to 1 T/cm are achieved. A rich phenomenology is observed,
ranging from flattened drops caused by the magnetic attraction to drops
extended normally to the substrate because of the normal traction of the
magnetic field. We find that the former effect can be conveniently
described in terms of an effective Bond number that compares the effective drop attraction with the capillary force, whereas the
drop’s vertical elongation is effectively expressed by a dimensionless number S, which compares the pressure jump at the
ferrofluid interface because of the magnetization with the capillary pressure.