Mixed Convection in Pipe and Duct Flows With Strong Magnetic Fields

2021 ◽  
Vol 73 (1) ◽  
Author(s):  
Oleg Zikanov ◽  
Ivan Belyaev ◽  
Yaroslav Listratov ◽  
Peter Frick ◽  
Nikita Razuvanov ◽  
...  
Keyword(s):  
Mixed Convection ◽  
Fusion Reactor ◽  
Extreme Temperature ◽  
High Amplitude ◽  
General Picture ◽  
Electrically Conducting ◽  
Reactor Technology ◽  
Electrically Conducting Fluid ◽  
Open Questions ◽  
Amplitude Fluctuations

Abstract An imposed strong magnetic field suppresses turbulence and profoundly changes the nature of the flow of an electrically conducting fluid. We consider this effect for the case of mixed convection flows in pipes and ducts, in which unique regimes characterized by extreme temperature gradients and high-amplitude fluctuations (the so-called magnetoconvective fluctuations) have been recently discovered. The configuration is directly relevant to the design of the liquid-metal components of future nuclear fusion reactors. This review presents the general picture of the flow transformation emerging from the recent studies, illustrates the key known facts, and outlines the remaining open questions. Implications for fusion reactor technology and novel experimental and numerical methods are also discussed.

scholarly journals Magneto-convective fluctuation during downward flow of liquid metal in a heated pipe in a transverse magnetic field

2021 ◽  
Vol 2057 (1) ◽  
pp. 012023
Author(s):  
P A Sardov ◽  
Ya I Listratov ◽  
I A Belyaev
Keyword(s):  
Magnetic Field ◽  
Liquid Metal ◽  
Extreme Temperature ◽  
High Amplitude ◽  
Transverse Magnetic ◽  
Electrically Conducting ◽  
Reactor Technology ◽  
Numerical Studies ◽  
Open Questions ◽  
Amplitude Fluctuations

Abstract An imposed strong magnetic field suppresses turbulence and profoundly changes the nature of the flow of an electrically conducting fluid. We consider this effect for the case of mixed convection flows in pipes and ducts, in which unique regimes characterized by extreme temperature gradients and high-amplitude fluctuations (the so-called magnetoconvective fluctuations) have been recently discovered. The configuration is directly relevant to the design of the liquid-metal components of future nuclear fusion reactors. This work presents the general picture of the flow transformation emerging from the recent numerical studies (DNS - Direct Numerical Simulation), illustrates the key known facts, and outlines the remaining open questions. Implications for fusion reactor technology and novel experimental and numerical methods are also discussed.

Mixed convection flow of an electrically conducting fluid in a vertical channel with boundary conditions of the third kind

2014 ◽  
Vol 92 (11) ◽  
pp. 1387-1396 ◽  
Author(s):  
J.C. Umavathi ◽  
A.J. Chamkha
Keyword(s):  
Mixed Convection ◽  
Average Velocity ◽  
Vertical Channel ◽  
Perturbation Parameter ◽  
Conducting Fluid ◽  
Integration Scheme ◽  
Electrically Conducting ◽  
Nusselt Numbers ◽  
Electrically Conducting Fluid ◽  
External Fluid

In this study, the effects of viscous and Ohmic dissipation in steady, laminar, mixed, convection heat transfer for an electrically conducting fluid flowing through a vertical channel is investigated in both aiding and opposing buoyancy situations. The plates exchange heat with an external fluid. Both conditions of equal and different reference temperatures of the external fluid are considered. First, the simpler cases of either negligible Brinkman number or negligible Grashof number are addressed with the help of analytical solutions. The combined effects of buoyancy forces and viscous dissipation are analyzed using a perturbation series method valid for small values of the perturbation parameter. To relax the conditions on the perturbation parameter, the governing equations are also evaluated numerically by a shooting technique that uses the classical explicit Runge–Kutta method of four slopes as an integration scheme and the Newton–Raphson method as a correction scheme. In the examined cases of velocity and temperature fields, the Nusselt numbers at both the walls and the average velocity are explored. It is found that the velocity profiles for an open circuit (E > 0 or E < 0) lie in between the short circuit (E = 0). The graphical results illustrating the effects of various parameters on the flow as well as the average velocity and Nusselt numbers are presented for open and short circuits. In the absence of electric field load parameter and Hartmann number, the results agree with Zanchini (Int. J. Heat Mass Transfer, 41, 3949 (1998)). Further, the analytical and numerical solutions agree very well for small values of the perturbation parameter.

Mixed Convective Flow of Electrically Conducting Fluid in a Vertical Cylindrical Annulus With Moving Walls Adjacent to a Radial Magnetic Field Along With Transpiration

2019 ◽  
Vol 141 (8) ◽  
Author(s):  
Ali Shakiba ◽  
Asghar B. Rahimi
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Mixed Convection ◽  
Conducting Fluid ◽  
Cylinder Wall ◽  
Radial Magnetic Field ◽  
Electrically Conducting ◽  
Flow And Heat Transfer ◽  
Cylindrical Annulus ◽  
Electrically Conducting Fluid

The steady, viscous flow and mixed convection heat transfer of an incompressible electrically conducting fluid within a vertical cylindrical annulus with moving walls are investigated. This annulus is under the influence of a radial magnetic field and the fluid is suctioned/injected through the cylinders' walls. An exact solution of the Navier–Stokes equations and energy equation is derived in this problem where heat is transferred from the hot cylinder walls with constant temperature to the cooler moving fluid. The role of the movement of the annulus walls is studied on the flow and heat transfer of the fluid within the annulus, for the first time. The effects of other parameters, including Prandtl number, Hartman number, mixed convection parameter, suction/injection parameter and ratio of the radius, on the behavior of the flow and heat transfer of the fluid is also considered. The results indicate that if, for example, the internal cylinder wall moves in the direction of z-axis and the external cylinder is stationary, the maximum and minimum heat transfer occur on the walls of internal and external cylinders, respectively. Moreover, the augmentation of the radius ratio between the two cylinders increases the rate of heat transfer and decreases the shear stress on the wall of the internal and external cylinders, however, the results on the wall of external cylinder are exactly the reverse. Consequently, by changing the effective parameters used in this paper, the flow of the fluid can be controlled and the heat transfer of the fluid can be improved.

scholarly journals Homotopy Analysis Solution of Hydromagnetic Mixed Convection Flow Past an Exponentially Stretching Sheet with Hall Current

2012 ◽  
Vol 2012 ◽  
pp. 1-26 ◽  
Author(s):  
Mohamed Abd El-Aziz ◽  
Tamer Nabil
Keyword(s):  
Magnetic Field ◽  
Mixed Convection ◽  
Convection Flow ◽  
Mixed Convection Flow ◽  
Electrically Conducting ◽  
Hall Parameter ◽  
Homotopy Analysis ◽  
Continuous Sheet ◽  
Exponentially Stretching ◽  
The Magnetic Field

The effect of thermal radiation on steady hydromagnetic heat transfer by mixed convection flow of a viscous incompressible and electrically conducting fluid past an exponentially stretching continuous sheet is examined. Wall temperature and stretching velocity are assumed to vary according to specific exponential forms. An external strong uniform magnetic field is applied perpendicular to the sheet and the Hall effect is taken into consideration. The resulting governing equations are transformed into a system of nonlinear ordinary differential equations using appropriate transformations and then solved analytically by the homotopy analysis method (HAM). The solution is found to be dependent on six governing parameters including the magnetic field parameterM, Hall parameterm, the buoyancy parameterξ, the radiation parameterR, the parameter of temperature distributiona, and Prandtl number Pr. A systematic study is carried out to illustrate the effects of these major parameters on the velocity and temperature distributions in the boundary layer, the skin-friction coefficients, and the local Nusselt number.

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