Deformation and motion by gravity and magnetic field of a droplet of water-based magnetic fluid on a hydrophobic surface

Motion and deformation of a water-based magnetic fluid on a hydrophobic surface were investigated under gravity and a magnetic field. Surface energy and the resultant contact angle of the magnetic fluid depend on the surfactant concentration. The fluid viscosity is governed mainly by magnetite concentration. The front edge of the droplet moved under a weak external field. The rear edge required a higher external field for movement. The forces of gravity and the magnetic field for moving of the front edge are almost equal. However, those of the rear edge are different. The motion of magnetic fluids by an external field depends on concentrations of surfactants and magnetic particles, the external field, and experimental assembly.

[1]  C. Tsouris,et al.  Agglomeration of magnetic particles and breakup of magnetic chains in surfactant solutions , 2002 .

[2]  Ichimura,et al.  Light-driven motion of liquids on a photoresponsive surface , 2000, Science.

[3]  B. Gates,et al.  Rhodium complex with ethylene ligands supported on highly dehydroxylated MgO: synthesis, characterization, and reactivity. , 2006, Langmuir : the ACS journal of surfaces and colloids.

[4]  Z. Kato,et al.  Adhesion and sliding of wet snow on a super-hydrophobic surface with hydrophilic channels , 2004 .

[5]  K. Hashimoto,et al.  Control of Water Droplets on Super-Hydrophobic Surfaces by Static Electric Field , 2002 .

[6]  A. Nakajima,et al.  Sliding mode transition of water droplet on the silicon surface coated with octadecyltrichlorosilane , 2003 .

[7]  Françoise Brochard-Wyart,et al.  Motions of droplets on hydrophobic model surfaces induced by thermal gradients , 1993 .

[8]  Blair Perot,et al.  Laminar drag reduction in microchannels using ultrahydrophobic surfaces , 2004 .

[9]  F. Brochard,et al.  Motions of droplets on solid surfaces induced by chemical or thermal gradients , 1989 .

[10]  P. C. Hiemenz,et al.  Principles of colloid and surface chemistry , 1977 .

[11]  Z. Kato,et al.  Adhesion and Sliding of Snow on Hydrophobic Solid Surface , 2002 .

[12]  I. Motoyama,et al.  Surface activities of ferrocene surfactants , 1995 .

[13]  C. Furmidge,et al.  Studies at phase interfaces. I. The sliding of liquid drops on solid surfaces and a theory for spray retention , 1962 .

[14]  Kazuhito Hashimoto,et al.  Effects of Surface Structure on the Hydrophobicity and Sliding Behavior of Water Droplets , 2002 .