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Beg O.A.,Sheffield Hallam University | Ghosh S.K.,Magnetohydrodynamics Research Program | Narahari M.,Petronas University of Technology
Chemical Engineering Communications | Year: 2011

We study theoretically the incompressible, viscous, oscillatory hydromagnetic Couette flow in a horizontal fluid-saturated highly permeable porous medium parallel-plate channel rotating about an axis perpendicular to the plane of the plates under the action of a uniform magnetic field, B0, inclined at an angle h to the axis of rotation. The flow is generated by the non-torsional oscillation of the lower plate of the channel. The reduced unsteady momentum equations are nondimensionalized with appropriate variables. Exact solutions under specified boundary conditions are obtained using the Laplace transform method (LTM). The flow regime is found to be controlled by a rotational parameter (K2), which is the reciprocal of the Ekman number (Ek), the square of the Hartmann magnetohydrodynamic number (M2), a porous medium permeability parameter (Kp), which is the inverse of the Darcy number (Da), oscillation frequency (x), dimensionless time (T), and magnetic field inclination (h). The influence of these parameters on the primary (u1) and secondary (v1) velocity field is presented graphically and studied in detail. Asymptotic behavior of the solutions is also examined for several cases of the square of the Hartmann number, rotation parameter, and oscillation angular frequency. The existence of modified Hartmann boundary layers is also identified. The present study has important applications in MHD (magnetohydrodynamic) energy generator flows, chemical engineering magnetic materials processing, conducting blood flows, and process fluid dynamics. © Taylor & Francis Group, LLC.


Beg O.A.,Sheffield Hallam University | Ghosh S.K.,Magnetohydrodynamics Research Program | Narahari M.,Petronas University of Technology | Beg T.A.,Engineering Mechanics and Renewable Energy Research
Chemical Engineering Communications | Year: 2011

We study theoretically the unsteady gravity-driven thermal convection flow of a viscous incompressible absorbing-emitting gray gas along an inclined plane in the presence of a pressure gradient and significant thermal radiation effects. The Rosseland diffusion flux model is employed to simulate thermal radiation effects. The momentum and energy conservation equations are nondimensionalized and solved exactly using the Laplace transform technique. Expressions are derived for the frictional shearing stress at the inclined plane surface and also the critical Grashof number. The effects of time (T), Grashof number (Gr), Boltzmann- Rosseland radiation parameter (K1), and plate inclination (α) on velocity (u) and temperature (θ) distributions are studied. The flow is found to be accelerated with increasing inclination of the plane, increasing free convection effects, and for greater thermal radiation contribution but decelerated with progression of time. Temperature is found to be enhanced with progression of time and with greater thermal radiation contribution. Applications of the model arise in solar energy collector analysis and industrial materials processing. © Taylor & Francis Group, LLC.


Zueco J.,Technical University of Cartagena | Beg O.A.,Sheffield Hallam University | Ghosh S.K.,Magnetohydrodynamics Research Program
Chemical Engineering Communications | Year: 2011

A mathematical model for the unsteady magnetohydrodynamic (MHD) laminar natural convection flow of a viscoelastic fluid from an infinite vertical porous plate to an isotropic, homogeneous, non-Darcian porous regime, with time-dependent suction, in the presence of a uniform transverse magnetic field, is studied. The generalized Beard-Walters rheological model is employed, which introduces a mixed third-order derivative into the momentum conservation equation. The transformed conservation equations are solved using the robust, well-tested computational procedure known as network simulation method (NSM). The NSM computations have shown that with an increase in viscoelasticity parameter (S) the flow accelerates considerably with time. Increasing magnetic field (M), however, retards the flow strongly with time. An increase in the Darcy number (Da) serves to augment the velocity (w) profiles, i.e., accelerate the flow in both the conducting (M ≠ 0) and nonconducting (M = 0) cases. Velocities also increase in value over time (τ). A velocity overshoot is identified close to the plate. A rise in the Forchheimer number (Fs), corresponding to an accentuation in the quadratic porous drag effect, induces a strong deceleration in the flow, in particular near the plate surface, for both conducting and nonconducting cases. Increasing buoyancy effects, as simulated via a rise in the thermal Grashof number (Gr), leads to a substantial retardation in the flow; this effect is enhanced with Lorentzian magnetic drag force. An increase in the suction parameter (A) causes a stronger adherence of the hydrodynamic boundary layer to the plate and leads to a reduction in velocities along the entire plate regime. A similar decrease in temperature (θ) is caused with increasing suction parameter (A). The results are of relevance in, for example, magneto-rheological materials processing operations and advanced hybrid magnetohydrodynamic energy systems exploiting non-Newtonian fluids. © Taylor & Francis Group, LLC.


Beg O.A.,Sheffield Hallam University | Makinde O.D.,Cape Peninsula University of Technology | Zueco J.,Technical University of Cartagena | Swapan,Technical University of Cartagena | Ghosh S.K.,Magnetohydrodynamics Research Program
World Journal of Modelling and Simulation | Year: 2012

A mathematical model is presented for the steady, axisymmetric, magnetohydrodynamic (MHD) flow of a viscous, Newtonian, incompressible, electrically-conducting liquid in a highly porous regime intercalated between two concentric rotating cylinders in the presence of a radial magnetic field. The porous medium is modeled using a Darcy-Forchheimer drag force approach to simulate the impedance effects of the porous medium fibers at both low velocities and also at higher velocities. The tangential and axial momentum equations are non-dimensionalized with the Nath transformations 33. and rendered into a system of nonlinear, second order, second degree partial differential conservation equations subject to appropriate nonslip boundary conditions. Solutions are obtained using both the MAPLE Library finite difference algorithm and the Network Simulation Method. The influence of Hartmann number (Ha), rotational Reynolds number (Re R), Darcy number (Da), Forchheimer number (Fs), pressure gradient parameter (α) and cylinder relative rotation rate (N) on the dimensionless tangential (U e) and axial (UZ) velocity components is studied in detail for the case where the cylinder walls are insulated. Excellent agreement is achieved between both methods. Applications of this study include hybrid porous media MHD power generators, magnetic materials processing and chemical engineering.


Ahmed S.,Rajiv Gandhi University | Anwar Beg O.,Sheffield Hallam University | Ghosh S.K.,Magnetohydrodynamics Research Program
Ain Shams Engineering Journal | Year: 2014

This study focuses analytically on the oscillatory hydromagnetic flow of a viscous, incompressible, electrically-conducting, non-Newtonian fluid in an inclined, rotating channel with non-conducting walls, incorporating couple stress effects. The model is then non-dimensionalized with appropriate variables and shown to be controlled by the inverse Ekman number (K2 = 1/Ek), the hydromagnetic body force parameter (M), channel inclination (α), Grashof number (Gr), Prandtl number (Pr), oscillation frequency (ω) and time variable (ωT). Analytical solutions are derived using complex variables. Excellent agreement is obtained between both previous and present work. The influence of the governing parameters on the primary velocity, secondary velocity, temperature (θ), primary and secondary flow discharges per unit depth in the channel, and frictional shear stresses due to primary and secondary flow, is studied graphically and using tables. Applications of the study arise in the simulation of the manufacture of electrically-conducting polymeric liquids and hydromagnetic energy systems exploiting rheological working fluids. © 2014 Production and hosting by Elsevier B.V.


Anwar Beg O.,Sheffield Hallam University | Ghosh S.K.,Magnetohydrodynamics Research Program | Ahmed S.,Heat Transfer and Fluid Mechanics Research | Beg T.,Bio Engineering Research
Journal of Mechanics in Medicine and Biology | Year: 2012

A mathematical study is conducted of the oscillatory hydromagnetic flow of a viscous, incompressible, electrically conducting, non-Newtonian bio-fluid in an inclined, rotating channel with nonconducting walls, incorporating couple stress effects. The constitutive equations for a couple-stress fluid and the Maxwell electromagnetic field equations are presented and then reduced to a set of coupled partial differential equations for the primary and secondary flow. The model is then nondimensionalized with appropriate variables and shown to be controlled by the inverse Ekman number (K 2 = 1/Ek), the hydromagnetic body force parameter (M), channel inclination (α), Grashof number (Gr), Prandtl number (Pr), oscillation frequency (ω), and time variable (ωT). Analytical solutions are derived using complex variables. The influence of the governing parameters on the primary velocity (u), secondary velocity (w), temperature (θ), primary and secondary flow discharges per unit depth in the channel (Q x, Q z), and frictional shear stresses due to primary and secondary flow (τ x, τ z), are studied graphically and using tables. Applications of the study arise in the simulation of the manufacture of electrically conducting bio-polymeric liquids and magneto-physiological flow devices. © 2012 World Scientific Publishing Company.

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