High magnetic field impact on the natural convection behaviour of a magnetic fluid

Abstract

An experimental analysis of high magnetic field impact on the natural convection of a paramagnetic fluid was conducted. Two geometries of experimental enclosures were investigated: Enclosure no. 1 with an aspect ratio of 0.5 (AR aspect ratio = height/width) and Enclosure no. 2 with a higher aspect ratio equal to 2.0. Various magnetic field inductions were analysed and representative parts of the obtained results are shown in the present paper. Estimations of the Nusselt number and spectral analysis of the fluid's behaviour were performed. The obtained results led to the conclusion that magnetic field has an immense impact on paramagnetic fluid flow, on heat transferred by the flow, as well as the flow structure. Introducing an additional buoyancy force to the system, acting toward intensification of the fluid motion, causes significant enhancement of the Nusselt number in both geometries. Additionally, a spectral analysis of temperature changes indicates that large flow structures occurring in natural convection cases at low frequencies, under the influence of magnetic field, transform towards smaller structures in the whole frequency band.

Identification of the Structures for Low Reynolds Number Flow in the Strong Magnetic Field

“…One promising aspect is the combination of the abovementioned abilities and nanofluid properties [10], which might lead to heat transfer modifications. The cavities of various shapes and aspect ratios have also been taken into consideration [11][12][13]. From a medical point of view, it is worth mentioning magnetic drug delivery, i.e., aerosols, in the human respiratory system [14].…”

An Analysis of a Laminar-Turbulent Transition and Thermal Plumes Behavior in a Paramagnetic Fluid Subjected to an External Magnetic Field

“…The transition from laminar to turbulent flow was determined as 3 × 10 7 for cubical geometry, and 4 × 10 7 to 1.3 × 10 8 for a tall enclosure (aspect ratio AR = height/width = 2) [33]. A comparison of thermo-magnetic convection, heat transfer and basic spectral analysis for vessels with aspect ratios 0.5 and 2.0 for the experimental results was presented in [34], indicating that the heat transfer enhancement, as well as fluid flow structure, strongly depends on the geometry height.…”