Counter-rotating flow in coaxial cylinders under an axial magnetic field

Mahfoud, Brahim; Laouari, A.; Hadjadj, Ahmed; Benhacine, H.

doi:10.1016/j.euromechflu.2019.06.009

Cited by 16 publications

(9 citation statements)

References 17 publications

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“…After that, the size of the hydrodynamic vortex drops slowly when the Ha is The second line of Fig. 3 shows the induced electric current lines, which show the existence of an electromagnetic vortex breakdown (Mahfoud et al 2019). It seems that both hydrodynamic and electromagnetic vortices are connected because the disappearance of these two vortices is at the same critical Hartmann number (in this case Hacr=18).…”

Section: Magnetic Effect On Vortex Breakdownmentioning

confidence: 89%

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: Magnetic Effect On Vortex Breakdownmentioning

confidence: 89%

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

2021

JAFM

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“…Physical properties of silicon melt at T m = 1683 K. [28] Parameter flow problems, as reviewed in various sources (Mahfoud al. ; [17] Fei Rao and Lan Peng [24] ), which can be expressed as follows:…”

Section: Mathematical Model and Numerical Methodologymentioning

confidence: 99%

“…[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. [15][16][17][18][19][20][21][22][23] The flow of electric conductive silicon melt in the presence of a magnetic field produces an induced current, which interacts with the magnetic field in turn. Then a Lorentz force in the opposite direction of the flow of silicon melt would be created.…”

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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“…The literature review on convection problems confirmed that a magnetic field is used to stabilize the perturbation in the fluid motion and control the velocity field (Mahfoud and Bessaїh 2012b;Mahfoud et al2016Mahfoud et al , 2019Mahfoud et al , 2020. After that, Bendjaghlouli et al (2019a,b) have discussed the influence of the geometry and the thermal gradient to generated small vortices with and without an applied magnetic field.…”

Section: Introductionmentioning

confidence: 97%

Stability of an Electrically Conducting Fluid Flow between Coaxial Cylinders under Magnetic field

Benhacine

Mahfoud

Salmi

2022

JAFM

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This research aims to investigate the vortex breakdown zone, the stability margin, and the fluid layers of the rotating flow between two vertical coaxial cylinders under the effect of thermal gradient and an axial magnetic field. The governing Navier-Stokes, temperature, and potential equations are solved using the finitevolume method. Three combinations of aspect ratios (γ) and Reynolds numbers (Re) are compared. The pumping action sets up a secondary circulation along the meridional plane of the annular gap. For certain combinations, the vortex breakdown bubble occurred near the inner wall. Bifurcation in form of multiple fluid layers becomes apparent when the temperature difference exceeds a critical value. These fluid layers play the role of thermal insulation and limit the heat transfer between the hot top and cold bottom of the coaxial cylinders. Both the vortex breakdown and fluid layers could be suppressed by the magnetic field; the increasing of Hartmann number (Ha) would reduce the number of fluid layers. Diagrams represent the effect of increasing Richardson number (Ri) on fluid layers are established. Then stability diagrams corresponding to the transition from the multiple fluid layers zone to the one fluid layer zone for increasing Prandtl number (Pr) are obtained.

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Counter-rotating flow in coaxial cylinders under an axial magnetic field

Cited by 16 publications

References 17 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

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

Stability of an Electrically Conducting Fluid Flow between Coaxial Cylinders under Magnetic field

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