scholarly journals Gravitation modulation impact on MHD free convection flow of micropolar fluid

2020 ◽  
Vol 17 (2) ◽  
pp. 199-218
Author(s):  
Sanjib Sengupta ◽  
Reshmi Deb

In this paper, a theoretical study is carried out on unsteady three dimensional, laminar, free convective flow of micropolar fluid with Hall effect, Joule heating and heat sink under gravitation modulation. A uniform transverse magnetic field is applied normal to the plate along the fluid region. The magnetic Reynolds number is considered to be small due to incomparability of applied and induced magnetic field, as such the influence of induced magnetic field can be neglected. The multi parameter perturbation technique is used to solve the governed dimensionless equations. The fluid velocity profile, temperature profile and the concentration profiles are discussed with the aid of graphs and tables. The coefficient of skin friction and couple stresses are numerically computed in addition to Nusselt number and Sherwood number. The result reveals that the linear velocity increases due to escalation in gravitation modulation parameter values but for intensification in values of gravitation modulation parameter, a reverse effect is observed for the rotational velocity. A comparative analysis shows that the skin friction coefficient is less in micropolar fluid than the corresponding Newtonian fluids.

Author(s):  
Obulesu Mopuri ◽  
Charankumar Ganteda ◽  
Bhagyashree Mahanta ◽  
Giulio Lorenzini

The main aim of this investigation is to study thermo diffusion, heat source/sink, Joule and chemical effects on heat transfer in MHD mixed convection flow and mass transfer past an infinite vertical plate with ohmic heating and viscous dissipation have been studied. We consider the mixed convection flow of an incompressible and electrically conducting viscous fluid such that x* -axis is taken along the plate in upward direction and y* -axis is normal to it. A transverse constant magnetic field is applied i.e., in the direction of y*-axis. Approximate solutions have been derived for velocity, temperature, concentration profiles, skin friction, rate of heat transfer and rate of mass transfer using perturbation technique. The obtained results are discussed with the help of graphs to observe the effect of various parameters like Grashof number (Gr), the modified Grashof number (Gm), magnetic parameter (M), Permeability parameter(K), Prandtl number (Pr), Heat Sink(Q), Radiation Parameter (F), Soret parameter (S0), Eckert number (E),Schmidt number(Sc) and Chemical reaction parameter(K0) taking two cases viz. Fluid velocity, temperature and concentration profiles are comparison with Pr=0.71(Air) and Pr =7 (Water) various parameters in cooled and heated plates. Case I: when Gr > 0 (flow on cooled plate), and Case II: Gr < 0, (flow on heated plate). Both the fluid velocity and concentration rising with the increment values of Soret parameter in the fluids Air and Water and also discussed skin friction, Nusselt number and Sherwood number in the fluid’s mercury, electrolytic solution, air and water. The novelty of this study is the consideration of simultaneous occurrence of radiation, heat absorption as well as thermo- diffusion in the magnetic field. It varies in several aspects such as non-dimensional parameters, analytical solutions, and graphical solutions, the analytic solution using the Perturbation technique, and numerical solution using Matlab software for the profile.


Author(s):  
Basant K. Jha ◽  
Peter B. Malgwi

AbstractThis study examines the impact of induced magnetic field and Hall current on steady fully developed hydromagnetic natural convection flow in a micro-channel under the action of an inclined magnetic field. The mathematical model responsible for the present physical situation is presented in a dimensionless form under relevant boundary conditions. The governing coupled equations are solved exactly. A parametric study of some physical parameters is conducted and a representative set of numerical results for the velocity field, the induced magnetic field, induced current density, volume flow rate, and skin friction on the micro-channel surfaces are illustrated graphically. It is observed that magnetic field inclination plays an important role in flow formation inside the micro-channel. Numerical computation reveals that the increase in inclination angle reduces the hydromagnetic drag leading to enhancement in primary fluid velocity, while the impact is just converse on the secondary fluid velocity. Furthermore, the increase in Hall current parameter increases the magnitude of the fluid velocity in both primary and secondary flow directions.


Author(s):  
Basant K Jha ◽  
Michael O Oni

This study examines the role of magnetic field on fully developed mixed convection flow of heat generating/absorbing fluid in a vertical micro-concentric annulus with velocity slip and temperature jump at the surfaces of the cylinders. Exact solution of momentum and energy equations are obtained separately in terms of Bessel’s function and modified Bessel’s function of first and second kind. The solutions obtained are graphically represented and the effects of pertinent parameters on flow formation and skin-friction are investigated in details. Results show that the role of magnetic field is to decrease fluid velocity as well as skin-friction at the outer surface of inner cylinder. In addition, reverse flow formation can be controlled by increasing magnetic field strength.


2008 ◽  
Vol 2008 ◽  
pp. 1-23 ◽  
Author(s):  
Kh. S. Mekheimer

We carry out the effect of the induced magnetic field on peristaltic transport of an incompressible conducting micropolar fluid in a symmetric channel. The flow analysis has been developed for low Reynolds number and long wavelength approximation. Exact solutions have been established for the axial velocity, microrotation component, stream function, magnetic-force function, axial-induced magnetic field, and current distribution across the channel. Expressions for the shear stresses are also obtained. The effects of pertinent parameters on the pressure rise per wavelength are investigated by means of numerical integrations, also we study the effect of these parameters on the axial pressure gradient, axial-induced magnetic field, as well as current distribution across the channel and the nonsymmetric shear stresses. The phenomena of trapping and magnetic-force lines are further discussed.


2016 ◽  
Vol 21 (3) ◽  
pp. 667-681 ◽  
Author(s):  
K.D. Singh

Abstract An unsteady mixed convection flow of a visco-elastic, incompressible and electrically conducting fluid in a hot vertical channel is analyzed. The vertical channel is filled with a porous medium. The temperature of one of the channel plates is considered to be fluctuating span-wise cosinusoidally, i.e., $T^* \left( {y^* ,z^* ,t^* } \right) = T_1 + \left( {T_2} - {T_ 1} \right)\cos \left( {{{\pi z^* } \over d} - \omega ^* t^* } \right)$ . A magnetic field of uniform strength is applied perpendicular to the planes of the plates. The magnetic Reynolds number is assumed very small so that the induced magnetic field is neglected. It is also assumed that the conducting fluid is gray, absorbing/emitting radiation and non-scattering. Governing equations are solved exactly for the velocity and the temperature fields. The effects of various flow parameters on the velocity, temperature and the skin friction and the Nusselt number in terms of their amplitudes and phase angles are discussed with the help of figures.


Author(s):  
R. Nandkeolyar ◽  
M. Narayana ◽  
S. S. Motsa ◽  
P. Sibanda

The steady hydromagnetic flow of a viscous, incompressible, perfectly conducting, and heat absorbing fluid past a vertical flat plate under the influence of an aligned magnetic field is studied. The flow is subject to mixed convective heat transfer. The fluid is assumed to have a reasonably high magnetic Prandtl number which causes significant-induced magnetic field effects. Such fluid flows find application in many magnetohydrodynamic devices including MHD power-generation. The effects of viscous dissipation and heat absorption by the fluid are investigated. The governing nonlinear partial differential equations are converted into a set of nonsimilar partial differential equations which are then solved using a spectral quasi-linearization method (SQLM). The effects of the important parameters on the fluid velocity, induced magnetic field, fluid temperature and as well as on the coefficient of skin-friction and the Nusselt number are discussed qualitatively.


2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Hasan Nihal Zaidi ◽  
Mohammed Yousif ◽  
S. Nazia Nasreen

The study scrutinizes the effects of thermal radiation, heat generation, and induced magnetic field on steady, fully developed hydromagnetic free convection flow of an incompressible viscous and electrically conducting couple stress fluid in a vertical channel. The channel walls are maintained at an isoflux-isothermal condition, such that the left channel wall is maintained at a constant heat flux. In contrast, the right channel wall is maintained at a constant temperature. The governing simultaneous equations are solved analytically utilizing the method of undetermined coefficient, and closed form solutions in dimensionless form have been acquired for the velocity field, the induced magnetic field, and the temperature field. The expression for the induced current density has been also obtained. A parametric study for the velocity, temperature, and induced magnetic field profiles, as well as for the skin-friction coefficient, Nusselt number, and induced current density, is conducted and discussed graphically.


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