Rayleigh-Bénard Convection of Paramagnetic Liquid under a Magnetic Field from Permanent Magnets

Abstract

The convection control is important in terms of the heat transfer enhancement and improvement of the applied devices and resultant products. In this study, the convection control by a magnetic field from block permanent magnets is numerically investigated on the Rayleigh-Bénard convection of paramagnetic fluid. To enhance the magnetic force from the available permanent magnets, pairs of alternating-pole magnets are employed and aligned near the bottom heated wall. The lattice Boltzmann method is employed for the computation of the heat and fluid flow with the consideration of buoyancy and magnetothermal force on the working fluid. It is found that, since the magnetic force at the junction of pair magnets becomes strong remarkably and in the same direction as the gravity, descending convection flow is locally enhanced and the pair of symmetrical roll cells near the magnet junction becomes longitudinal. The local heat transfer corresponds to the affected roll cell pattern; locally enhanced at the magnet junctions and low heat transfer area is shifted aside the magnet outer edge. The averaged Nusselt number on the hot wall also increases proportionally to the magnetic induction but it is saturated at high magnetic induction. This suggests the roll cell pattern is no more largely affected at extremely-high magnetic induction.

Mixed convection by buoyancy and magnetothermal forces

“…The reference temperature T0 was presumed at 293.15 K. The computational parameters are the Prandtl number, the Rayleigh number, and the dimensionless magnetic energy γ [17].…”

Magnetic Field Inhibition of Convective Heat Transfer in Magnetic Nanofluid

“…Another way to achieve the effect of the magnetic field on the parameters of thermal convection is to use electrically non-conductive weakly magnetic (para-and diamagnetic) fluids. Various manifestations of thermomagnetic convection phenomena of weakly magnetic fluids have been investigated in detail, experimentally, theoretically, and computationally, in a number of works (e.g., [8][9][10][11][12]).…”

Asymmetrical Thermal Boundary Condition Influence on the Flow Structure and Heat Transfer Performance of Paramagnetic Fluid-Forced Convection in the Strong Magnetic Field

“…In Reference [10], the application of the Lattice-Boltzmann method for thermo-magnetic convection mathematical description was proposed. The presentation of the passive magnetic heat transfer enhancement method, thermo-magnetic convection under no gravity conditions and the magnetic damping effect on the sloshing of liquid paramagnetic substances were studied in References [11][12][13] and Reference [14]. The issue of resonant enhancement in an enclosure filled with paramagnetic fluid due to the time-periodic magnetizing force was presented in Reference [15].…”