Keywords

Magnetic fluid, thermomagnetic convection

Abstract

In this work we studied the convective heat transfer in a magnetic fluid in both zero and applied magnetic fields. The natural convection is observed in a quasi-one dimensional magnetic fluid in a horizontal temperature gradient. The horizontal non-homogeneous magnetic fields were applied across the sample cell either parallel or anti-parallel to the temperature gradient. The temperature profile was measured by eight thermocouples and temperature sensitive paint. The flow velocity field and streamlines were obtained by optical flow method. Calculated Nusselt numbers, Rayleigh number, and Grashof number show that the convective flow is the main heat transfer mechanism in applied fields in our geometry. It was found that when the field gradient is parallel with temperature gradient, the fields enhance the convective heat transfer while the fields inhibit it in anti-parallel configuration by analyzing the temperature difference across the sample, flow patterns, and perturbation Q field in applied fields. Magnetic Rayleigh number and magnetic Grashof number show that the thermomagnetic convections dominate in high magnetic fields. It is shown that the physical nature of the field effect is corresponding to the magnetic body force which is perpendicular to the gravity in our experiments. When the direction of the magnetic body force is same with temperature gradient in parallel configuration, the body force increases the convective heat transfer; while it has opposite effect in anti-parallel configuration. Our study will not only shed light on the fundamental mechanisms for thermomagnetic convection but also help to develop the potential field-controlled heat transfer devices.

Notes

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Graduation Date

2015

Semester

Fall

Advisor

Luo, Weili

Degree

Doctor of Philosophy (Ph.D.)

College

College of Sciences

Department

Physics

Degree Program

Physics

Format

application/pdf

Identifier

CFE0005957

URL

http://purl.fcla.edu/fcla/etd/CFE0005957

Language

English

Release Date

12-15-2016

Length of Campus-only Access

1 year

Access Status

Doctoral Dissertation (Open Access)

Subjects

Dissertations, Academic -- Sciences; Sciences -- Dissertations, Academic

Included in

Physics Commons

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