Transients and turbulence pockets in thermal convection of paramagnetic fluid subjected to strong magnetic field gradients

Abstract

We performed combined experimental and numerical studies of the flow and heat transfer of a paramagnetic fluid inside a differentially heated cubical enclosure subjected to various strong non-uniform magnetic field gradients. Two different heating scenarios are considered: unstable (heated from below) and stable (heated from above) initial thermal stratification. In contrast to the previously reported studies in literature, which observed solely laminar flow regimes, we investigated also appearance and sustenance of the periodic-and fully transient-flow motions for the very first time. This was consequence of using significantly stronger magnetic field strength (up to 10 T experimentally, and up to 15 T numerically) than those used in previous studies (up to 5 T). Detailed comparison between experiments and numerical simulations are performed and generally very good agreements were obtained.

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

“…Szabo and Fruh [29] analyzed numerical transition from natural convection to thermomagnetic convection in a square enclosure for small values of magnetic induction (up to 1T) for a heated from the sides configuration and described the formulation of side thermal plume with increasing magnetic influence. Pyrda, Wróbel and Kenjeres [30][31][32] undertook the subject of extending the analysis of thermo-magnetic convection in the Rayleigh-Benard configuration to the transitional and turbulent regimes for a cubical enclosure. They provided detailed insight into the fluid flow and heat transfer changes under the influence of an external magnetic field over a range of parameters (different Prandtl numbers and values of imposed magnetic field 0-15T) and determined three flow regimes: a transient regime (Ra TM ≤ 3 × 10 7 ), a regime where a thermo-magnetic mechanism dominates (3 × 10 7 < Ra TM ≤ 3 × 10 8 ), and an additional wall heat transfer regime for Ra TM ≥ 3 × 10 8 .…”

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

“…Bednarz et al [3][4][5] studied heat transfer and influence of different inclinations of a magnetic field on a paramagnetic fluid in cubical geometry in side-heated configurations. Kenjeres et al [6,7] and Pyrda et al [8] investigated various aspects, e.g. Prandtl number and magnetic susceptibility in transient and turbulent flow regimes in a cubical enclosure.…”

Effect of a Magnetic Quadrupole Field on Entropy Generation in Thermomagnetic Convection of Paramagnetic Fluid with and without a Gravitational Field

“…Bednarz et al [8,20,21] analyzed the effect of the Rayleigh number, inclined angle, and the location of the electric coil on heat transfer of the paramagnetic fluid. Kenjeres et al [22,23], numerically and experimentally, studied the flow and heat transfer of a paramagnetic fluid under various strong non-uniform magnetic field gradients. The combined effects of thermal buoyancy force and magnetic force were considered.…”