Hydrodynamic instabilities in swirling flow under axial magnetic field

Laouari, A.; Mahfoud, Brahim; Bessaïh, Rachid; Hadjadj, Ahmed

doi:10.1016/j.euromechflu.2020.08.006

Cited by 18 publications

(9 citation statements)

References 16 publications

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“…The Hartmann layers play the role of thermal insulation and favor the conduction, which in turn reduces the rate of heat transfer (Mahfoud and Bessaїh, 2016). The influence of a magnetic field on the vortex breakdown is well known from the recent of Laouari et al(2021). However, the electromagnetic force reducing the pressure gradient and damping the axial movement of fluid, which tends to suppress the small vortex (counter-rotating flow).…”

Section: Resultsmentioning

confidence: 99%

“…Some researchers have studied the possibility to use a magnetic field to control the behavior of the vortex breakdown and stabilize the flow (Yu et al 2013;Dash and Singh 2019). Laouari et al (2021) have recently studied the effects of the electrical conductivity of the wall on the vortex breakdown position and its disappearance in the different regimes. The results obtained be seen that the vortex breakdown is eliminated after the magnitude of the magnetic field surpasses a critical value.…”

Section: Introductionmentioning

confidence: 99%

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Effects of an Axial Magnetic Field on Vortex Breakdown and Fluid Layer

2021

JAFM

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The effects of an axial magnetic field on both the vortex breakdown process and fluid layers development in a cylindrical container filled with a conducting viscous fluid are numerically analyzed by using the Generalized Integral Transform Technique (GITT) with a stream function-only formulation. A temperature gradient is imposed in the axial direction on the swirling flow which is advanced by the rotation of the bottom disk under the stabilizing effect of the external magnetic field. Flows are studied for a range of parameters: the Richardson number, Ri, 0 ≤Ri ≤2.0; and three values of the Prandtl number are investigated, Pr = 0.025 (liquid Mercury), 0.032 ( PbLi 17 alloy), and 0.065 (the molten lithium). Three combinations of aspect ratios (H/R) and Reynolds numbers are compared: (case A: Re=1500, H/R=1.5); (case B: Re=1855, H/R=2.0) and (case C: Re=2400, H/R=2.5). The results reveal that the increase in the values of Hartmann number, Ha suppresses the vortex breakdown in the isothermal case and reduces the number of fluid layers in the layering case. The stability diagram (Hacr-Ri) corresponding to the transition from the multiple fluid layers zone to the one fluid layer zone for increasing Prandtl number is obtained.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Effects of an Axial Magnetic Field on Vortex Breakdown and Fluid Layer

2021

JAFM

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“…[21,22]. Laouari et al [23] recently investigated the impact of the axial magnetic field and the conductivities of the walls on the location of breakdown in two regimes (stationary and oscillatory).…”

Section: Introductionmentioning

confidence: 99%

Buoyancy force and magnetic field effects on laminar vortex breakdown and fluid layers

MAHFOUD

Moussaoui

2023

Journal of Thermal Engineering

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In this study, the Generalized Integral Transformation Technique (GITT) is used to describe the effect of buoyancy force and magnetic field on the vortex breakdown process generated by the rotation of an electrically conductive fluid. A magnetic field is positioned vertically to stabilize the swirling flow caused by the rotation of the bottom disc of a cylindrical recipient. Three fluids were compared in this study where the range of Richardson number is 0 ≤Ri ≤2.0. When the temperature difference is greater than Ri = 0.1, many layers become visible. These stratified flu id layers act as thermal insulators. In the case of stratification, the increased magnetic field reduces the total number of layers formed in the fluid. The influence of gradient temperature on the distribution of the layers generated is discussed. The limitations between the multilayer structure and the monolayer structure for three fluids are calculated as a function of the flow parameters.

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“…[4][5][6] The application of the magnetic field on the rotating flows is a promising and practical technology, the researchers are very interested in it and there is a progression in this field of research. [7][8][9] Also, the magnetic field can be used DOI: 10.1002/crat.202300025 to control the heat transfer in the nanofluid flow. [10][11][12][13][14] To control flow physics, several types of research including the present study, impose a magnetic field on annular geometries or two coaxial cylinders where an electrically conductive fluid flows in the annular space.…”

Section: Introductionmentioning

confidence: 99%

MHD Effect on the Thermocapillary Silicon Melt Flow in Various Annular Enclosures

Mahfoud

Azzoug

2023

Cryst. Res. Technol.

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To simulate thermocapillary magnetohydrodynamic (MHD) convection in different shallow annular enclosures filled with silicon melt, a 3D numerical approach using an implicit finite volume formulation is used. Radiation is emitted upward from the annular enclosure's free top surface, the bottom one heated vertically and is subjected to an external magnetic field. The steady and unsteady thermocapillary MHD flow in four annular enclosures (R = 0.5, 0.6, 0.7, and 0.8) field is studied. The effects of varying the annular gaps, R, on the hydrothermal wave number and azimuthal pattern are obtained. The effects of the magnetic field on azimuthal velocity, temperature disturbances, and the transition from oscillatory to steady flow are also depicted. The results reveal that: hydrothermal waves m = 4, m = 6 and m = 8 are observed in steady flow for R = 0.7, R = 0.6 and R = 0.5, respectively. Oscillatory flows dominated by a hydrothermal wave m = 3 are found also when R = 0.8. The azimuthal velocity and temperature fluctuations at the free surface decrease as the magnitude of the magnetic field (Ha) increases, and the oscillatory flow would turn steady when Ha exceeds a critical value.

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Hydrodynamic instabilities in swirling flow under axial magnetic field

Cited by 18 publications

References 16 publications

Effects of an Axial Magnetic Field on Vortex Breakdown and Fluid Layer

Effects of an Axial Magnetic Field on Vortex Breakdown and Fluid Layer

Buoyancy force and magnetic field effects on laminar vortex breakdown and fluid layers

MHD Effect on the Thermocapillary Silicon Melt Flow in Various Annular Enclosures

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