Influence of Temperature on the Magneto-Dielectrics Effect of Oil-Based Ferrofluid

Kúdelčík, Jozef; Hardoň, Štefan; Bury, Peter; Τimko, M.; Kopčanský, P.

doi:10.12693/aphyspola.133.483

Cited by 1 publication

(1 citation statement)

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“…The mean thermal transfer of ferrofluid was claimed to rise more than 64% when the magnetic field is applied. Kúdelčíka et al [20] presented the thermal effects on the magneto-dielectrics behavior of oil-based ferrofluids by dielectric spectroscopy. The natural convection for a ferrofluid in a trapezoid cavity in the presence of an inclined magnetic field was examined in [21].…”

Section: Introductionmentioning

confidence: 99%

A New Theoretical Approach of Wall Transpiration in the Cavity Flow of the Ferrofluids

Siddiqui

Türkyılmazoğlu

2019

Micromachines

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An idea of permeable (suction/injection) chamber is proposed in the current work to control the secondary vortices appearing in the well-known lid-driven cavity flow by means of the water based ferrofluids. The Rosensweig model is conveniently adopted for the mathematical analysis of the physical problem. The governing equation of model is first transformed into the vorticity transport equation. A special finite difference method in association with the successive over-relaxation method (SOR) is then employed to numerically simulate the flow behavior. The effects of intensity of magnetic source (controlled by the Stuart number), aspect ratio of the cavity, rate of permeability (i.e., α p = V 0 U ), ratio of speed of suction/injection V 0 to the sliding-speed U of the upper wall of a cavity, and Reynolds number on the ferrofluid in the cavity are fully examined. It is found that the secondary vortices residing on the lower wall of the cavity are dissolved by the implementation of the suction/injection chamber. Their character is dependent on the rate of permeability. The intensity of magnetic source affects the system in such a way to alter the flow and to transport the fluid away from the magnetic source location. It also reduces the loading effects on the walls of the cavity. If the depth of cavity (or the aspect ratio) is increased, the secondary vortices join together to form a single secondary vortex. The number of secondary vortices is shown to increase if the Reynolds number is increased for both the clear fluid as well as the ferrofluids. The suction and injection create resistance in settlement of solid ferroparticles on the bottom. The results obtained are validated with the existing data in the literature and satisfactory agreement is observed. The presented problem may find applications in biomedical, pharmaceutical, and engineering industries.

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Section: Introductionmentioning

confidence: 99%