scholarly journals Mathematical Analysis of Hall Effect on Transient Hartman Flow about a Rotating Horizontal Permeable Surface in a Porous Medium under Inclined Magnetic Field

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
M. Suresh ◽  
A. Manglik
Keyword(s):  
Magnetic Field ◽  
Porous Medium ◽  
Hall Effect ◽  
Saturated Porous Medium ◽  
Flow Behavior ◽  
Darcy Number ◽  
Flow Equations ◽  
Electrically Conducting ◽  
Laplace Transform Technique ◽  
The Magnetic Field

This paper proposes the exact solution for unsteady flow of a viscous incompressible electrically conducting fluid past a impulsively started infinite horizontal surface which is rotating with an angular velocity embedded in a saturated porous medium under the influence of strong magnetic field with hall effect. Our study focuses on the change of direction of the external magnetic field on the flow system which leads to change in the flow behavior and skin frictional forces at the boundary. Systems of flow equations are solved using Laplace transform technique. The impacts of control parameters Hartman number, rotation of the system, hall effect, inclination of the magnetic field, and Darcy number on primary and secondary velocities are shown graphically, skin friction at horizontal boundary in tabular form. For validating our results, in the absence of permeability of the porous medium and inclination of the magnetic field the results are in good agreement with the published results.

scholarly journals Heat Transfer to MHD Oscillatory Viscoelastic Flow in a Channel Filled with Porous Medium

2012 ◽  
Vol 2012 ◽  
pp. 1-5 ◽  
Author(s):  
Rita Choudhury ◽  
Utpal Jyoti Das
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Porous Medium ◽  
Radiative Heat ◽  
Saturated Porous Medium ◽  
Transverse Magnetic ◽  
Viscoelastic Flow ◽  
Viscoelastic Parameter ◽  
Flow Parameters ◽  
The Magnetic Field

The combined effect of a transverse magnetic field and radiative heat transfer on unsteady flow of a conducting optically thin viscoelastic fluid through a channel filled with saturated porous medium and nonuniform walls temperature has been discussed. It is assumed that the fluid has small electrical conductivity and the electromagnetic force produced is very small. Closed-form analytical solutions are constructed for the problem. The effects of the radiation and the magnetic field parameters on velocity profile and shear stress for different values of the viscoelastic parameter with the combination of the other flow parameters are illustrated graphically, and physical aspects of the problem are discussed.

Combined Effect of Temperature Modulation and Magnetic Field on the Onset of Convection in an Electrically Conducting-Fluid-Saturated Porous Medium

2008 ◽  
Vol 130 (5) ◽  
Author(s):  
B. S. Bhadauria
Keyword(s):  
Magnetic Field ◽  
Porous Medium ◽  
Saturated Porous Medium ◽  
Effect Of Temperature ◽  
Temperature Modulation ◽  
Vertical Magnetic Field ◽  
Onset Of Convection ◽  
Electrically Conducting ◽  
Electrically Conducting Fluid ◽  
Fluid Saturated Porous Medium

The effect of temperature modulation on the onset of thermal convection in an electrically conducting fluid-saturated-porous medium, heated from below, has been studied using linear stability analysis. The amplitudes of temperature modulation at the lower and upper surfaces are considered to be very small. The porous medium is confined between two horizontal walls and subjected to a vertical magnetic field; flow in porous medium is characterized by Brinkman–Darcy model. Considering only infinitesimal disturbances, and using perturbation procedure, the combined effect of temperature modulation and vertical magnetic field on thermal instability has been studied. The correction in the critical Rayleigh number is calculated as a function of frequency of modulation, Darcy number, Darcy Chandrasekhar number, magnetic Prandtl number, and the nondimensional group number χ. The influence of the magnetic field is found to be stabilizing. Furthermore, it is also found that the onset of convection can be advanced or delayed by proper tuning of the frequency of modulation. The results of the present model have been compared with that of Darcy model.

Magnetohydrodynamic flow of non-Newtonian visco-elastic fluid through a porous medium near an accelerated plate

2003 ◽  
Vol 81 (11) ◽  
pp. 1249-1269 ◽  
Author(s):  
Nabil TM Eldabe ◽  
Galal M Moatimid ◽  
Hoda Sm Ali
Keyword(s):  
Magnetic Field ◽  
Porous Medium ◽  
Velocity Distribution ◽  
Skin Friction ◽  
Equations Of State ◽  
Equations Of Motion ◽  
Electrically Conducting ◽  
Stress Strain Relation ◽  
Solid Plate ◽  
The Magnetic Field

An exact solution is obtained for the unsteady flow of an electrically conducting visco-elastic incompressible fluid through a porous medium on an infinite flat plate. The fluid under consideration obeys the rheological equations of state due to the Walters stress–strain relation. The plate is accelerated in the presence of a uniform magnetic field. The analysis includes the case of a solid plate as well as a porous one. The solution of the equations of motion is obtained by the use of a Laplace transform. The effects of the elasticity, magnetic field, permeability of the porous medium, and the suction of the plate on the velocity distribution, as well as on skin friction, are discussed. The analytical results are confirmed numerically. It is found that the velocity distribution increases with an increase of both elasticity and permeability, while it decreases as the magnetic parameter increases. It is also found that the skin friction decreases with an increase in the magnetic field and elasticity parameters, while it increases with an increase of both the permeability of the porous medium and the suction of the plate.PACS Nos.: 47.50.+d, 47.55.Mh, 47.85.Dh

Effects of uniform or non-uniform heating at bottom wall on MHD mixed convection in a porous cavity saturated by nanofluid

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Subramanian Muthukumar ◽  
Selvaraj Sureshkumar ◽  
Arthanari Malleswaran ◽  
Murugan Muthtamilselvan ◽  
Eswari Prem
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Transfer Rate ◽  
Hartmann Number ◽  
Volume Fraction ◽  
Solid Volume Fraction ◽  
Darcy Number ◽  
Bottom Wall ◽  
Uniform Heating ◽  
The Magnetic Field

Abstract A numerical investigation on the effects of uniform and non-uniform heating of bottom wall on mixed convective heat transfer in a square porous chamber filled with nanofluid in the appearance of magnetic field is carried out. Uniform or sinusoidal heat source is fixed at the bottom wall. The top wall moves in either positive or negative direction with a constant cold temperature. The vertical sidewalls are thermally insulated. The finite volume approach based on SIMPLE algorithm is followed for solving the governing equations. The different parameters connected with this study are Richardson number (0.01 ≤ Ri ≤ 100), Darcy number (10−4 ≤ Da ≤ 10−1), Hartmann number (0 ≤ Ha ≤ 70), and the solid volume fraction (0.00 ≤ χ ≤ 0.06). The results are presented graphically in the form of isotherms, streamlines, mid-plane velocities, and Nusselt numbers for the various combinations of the considered parameters. It is observed that the overall heat transfer rate is low at Ri = 100 in the positive direction of lid movement, whereas it is low at Ri = 1 in the negative direction. The average Nusselt number is lowered on growing Hartmann number for all considered moving directions of top wall with non-uniform heating. The low permeability, Da = 10−4 keeps the flow pattern same dominating the magnetic field, whereas magnetic field strongly affects the flow pattern dominating the high Darcy number Da = 10−1. The heat transfer rate increases on enhancing the solid volume fraction regardless of the magnetic field.

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.

Gas-ionizing shocks in a magnetic field

1967 ◽  
Vol 1 (1) ◽  
pp. 37-54 ◽  
Author(s):  
M. D. Cowley
Keyword(s):  
Magnetic Field ◽  
Electric Field ◽  
Wave Speed ◽  
Normal Velocity ◽  
Electrically Conducting ◽  
Shock Stability ◽  
The Face ◽  
Arbitrary Velocity ◽  
Flow Plane ◽  
The Magnetic Field

Ionizing shocks for plane flows with the magnetic field lying in the flow plane are considered. The gas is assumed to be electrically conducting downstream, but non-conducting upstream. Shocks whose downstream state has a normal velocity component less than the slow magneto-acoustic-wave speed and whose upstream state is supersonic are found to be non-evolutionary in the face of plane magneto-acoustic disturbances, unless the upstream electric field in a frame of reference where the gas is at rest is arbitrary. Velocity conditions are also determined for shock stability with the electric field not arbitrary.Shock structures are found for the case of large ohmic diffusion, the initial temperature rise and ionization of the gas being caused by a thin transition having the properties of an ordinary gasdynamic shock. For the case where shocks are evolutionary when the upstream electric field is arbitrary, the shock structure requirements only restrict the electric field by limiting the range of possible values. When shocks are evolutionary with the electric field not arbitrary, they can only have a structure for a particular value of the electric field. Limits to the current carried by ionizing shocks and the effects of precursor ionization are discussed qualitatively.

Magnetostrictive Self-Diagnosing Smart Bolts

2014 ◽  
Author(s):  
Vladislav Sevostianov
Keyword(s):  
Magnetic Field ◽  
Plastic Deformation ◽  
Magnetic Fields ◽  
Hall Effect ◽  
Stress Level ◽  
Experimental Validation ◽  
Rock Bolts ◽  
Three Point Bending ◽  
Bending Loading ◽  
The Magnetic Field

The paper presents the concept of self-diagnosing smart bolts and its experimental validation. In the present research such bolts are designed, built, and experimentally tested. As a key element of the design, wires of Galfenol (alloy of iron and gallium) are used. This material shows magnetostrictive properties, and, at the same time, is sufficiently ductile to follow typical deformation of rock bolts, and is economically affordable. Two types of Galfenol were used: Ga10Fe90 and Ga17Fe83. The wires have been installed in bolts using two designs — in a drilled central hole or in a cut along the side — and the bolts were tested for generation of the magnetic field under three-point bending loading. To measure the magnetic field in the process of deformation, a magnetometer that utilizes the GMR effect was designed, built, and compared with one utilizing the Hall effect. It is shown that (1) magnetic field generated by deformation of the smart bolts at the stress level of plastic deformation is sufficient to be noticed by the proposed magnetometer; however, the magnetometer using Hall effect is insufficient; (2) Ga10Fe90 produces higher magnetic fields than Ga17Fe83; (3) the magnetic field in plastically bended bolts is relatively stable with time.

scholarly journals Magneto-rotatory compressible couple-stress fluid heated from below in porous medium

2016 ◽  
Vol 38 (1) ◽  
pp. 55-63
Author(s):  
Chander Bhan Mehta
Keyword(s):  
Magnetic Field ◽  
Porous Medium ◽  
Couple Stress ◽  
Normal Modes ◽  
Sufficient Conditions ◽  
Couple Stress Fluid ◽  
Onset Of Convection ◽  
Medium Permeability ◽  
Effects Of Rotation ◽  
The Magnetic Field

Abstract The study is aimed at analysing thermal convection in a compressible couple stress fluid in a porous medium in the presence of rotation and magnetic field. After linearizing the relevant equations, the perturbation equations are analysed in terms of normal modes. A dispersion relation governing the effects of rotation, magnetic field, couple stress parameter and medium permeability have been examined. For a stationary convection, the rotation postpones the onset of convection in a couple stress fluid heated from below in a porous medium in the presence of a magnetic field. Whereas, the magnetic field and couple stress postpones and hastens the onset of convection in the presence of rotation and the medium permeability hastens and postpones the onset of convection with conditions on Taylor number. Further the oscillatory modes are introduced due to the presence of rotation and the magnetic field which were non-existent in their absence, and hence the principle of exchange stands valid. The sufficient conditions for nonexistence of over stability are also obtained.

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