Ferrofluids have been vastly wooed in diverse areas of engineering and research. This contribution briefly exposes some concepts specific to ferrofluids and how they relate to recent applications emerging in chemical engineering, including mass transfer enhancement, momentum transfer in laminar and turbulent pipe flows and in porous media flows, and the motion of magnetic nanoparticles in gas-l...

The spectral response of a Bragg grating reflector inscribed in a microstructured optical fibre is tuned by employing an infiltrated ferrofluid, while modifying the overlap of the ferrofluidic medium with the grating length. Significant spectral changes in terms of Bragg grating wavelength shift and extinction ratio were obtained under static magnetic field actuation. Spectral measurements reve...

This paper presents an approach to establish the analytical formula for the force acting on a non-magnetic disc plunged into a ferrofluid, due to the effect of a magnetic field gradient generated by the magnetic inductor of the actuator. The expression of the force acting on a magnetizable body placed in a magnetic field was used for the particular conditions imposed by the actuator configurati...

Ferrofluids are strongly paramagnetic liquids. We study the behavior of ferrofluid droplets confined between two parallel plates with a weak applied field parallel to the plates. The droplets elongate under the applied field to reduce their demagnetizing energy and reach an equilibrium shape where the magnetic forces balance against the surface tension. This elongation varies logarithmically wi...

In the present work we report on the behavior of ferrofluid microdrops in an immiscible nonmagnetic carrier fluid and vice versa subjected to the action of magnetic fields. Our experiments evidence previously unexplored instability and flow patterns. We investigated the instabilities initiated by constant magnetic field and by combined action of constant and rotating magnetic fields. The observ...

The benefit of transformer oil seeded with magnetic nanoparticles (forming a oil-based ferrofluid) is numerically studied in an axisymmetric model 40 kVA transformer. maximum temperature the system decreased by 2.2 °C when using ferrofluid instead oil. This effect mainly due to body force, which modifies convective flow and enhances heat transfer. leakage field highly localized limits thermomag...

this paper provides an overview of how the surface properties of ferromagnetic nanoparticles dispersed in fluids is modified by natural and biocompatible polymers. among common magnetic nanoparticles, magnetite (fe3o4) and maghemite (g-fe203) are popular candidates because of their biocompatibility. natural polymeric coating materials are the most commonly used biocompatible magnetic nanopartic...

Abstract The viscosity of ferrofluid has a vital role in liquid sealing the hard disk drives, biomedical applications as drug delivery, hyperthermia, and magnetic resonance imaging. theoretical expressions for its limitation are presented detail this article. A qualitative comparison experimental results is also shown. In absence field, depends on volume concentration nanoparticles, including s...

The aggregation of magnetic particles in the presence of a magnetic field is the basic phenomenon which underlies all the physics of magnetorheological (MR) fluids. Although these interactions are well understood when the suspending fluid is a simple liquid, new MR fluids based on dispersion of magnetic microparticles in a ferrofluid or MR elastomers based on dispersion of magnetic particles in...

PURPOSE To present a novel design of an implantable glaucoma valve based on ferrofluidic nanoparticles and to compare it with a well-established FDA approved valve. SETTING Massachusetts Eye & Ear Infirmary, Boston, USA. METHODS A glaucoma valve was designed using soft lithography techniques utilizing a water-immiscible magnetic fluid (ferrofluid) as a pressure-sensitive barrier to aqueous ...