Hydromagnetic Free Convection Research Articles

The Analysis of Hydromagnetic Free Convection Heat and Mass Transfer Flow over a Stretching Vertical Plate with Suction

A general analysis has been developed to study the combined effect of the free convective heat and mass transfer on the unsteady two-dimensional boundary layer flow over a stretching vertical plate. The flow is subject to magnetic field normal to the plate. The governing nonlinear partial differential equations have been reduced to the coupled nonlinear ordinary differential equations by the similarity transformations. The resulting equations are solved numerically by using Runge-Kutta the shooting technique. The effects of the Magnetic field Parameter M, buoyancy parameter N, Prandtl number Pr and Schmidt number Sc are examined on the velocity, temperature and concentration profiles. Numerical data for the skin-friction coefficients, Nusselt and Sherwood numbers have been tabulated for various parametric conditions.

Effect of chemical reaction and thermal radiation on heat and mass transfer flow of MHD micropolar fluid in a rotating frame of reference

This paper studies the effect of first order chemical reaction and thermal radiation on hydromagnetic free convection heat and mass transfer flow of a micropolar fluid via a porous medium bounded by a semi-infinite porous plate with constant heat source in a rotating frame of reference. The plate is assumed to oscillate in time with constant frequency so that the solutions of the boundary layer are the same oscillatory type. The dimensionless governing equations for this investigation are solved analytically using small perturbation approximation. The effect of the various dimensionless parameters entering into the problem on the velocity, temperature and concentration profiles across the boundary layer are investigated through graphs. Also the results of the skin friction coefficient, couple stress coefficient, the rate of heat and mass transfer at the wall are prepared with various values of the parameters.

A Mathematical Model for Magnetohydrodynamic Convection Flow in a Rotating Horizontal Channel with Inclined Magnetic Field, Magnetic Induction and Hall Current Effects

Closed-form and asymptotic solutions are derived for the steady, fully-developed hydromagnetic free and forced convection flow in a rotating horizontal parallel-plate channel under the action of an inclined magnetic field and constant pressure gradient along the longitudinal axis of the channel. The magnetic field is strong enough to generate Hall current effects and the magnetic Reynolds number of sufficient magnitude that induced magnetic field effects are also present. Secondary flow is present owing to the Hall current effect. The channel plates are also taken to be electrically-conducting. The conservation equations are formulated in an (x, y, z) coordinate system and non-dimensionalized using appropriate transformations. The resulting non-dimensional coupled ordinary differential equations for primary and secondary velocity components and primary and secondary induced magnetic field components and transformed boundary conditions are shown to be controlled by the dimensionless pressure gradient parameter (px), Hartmann number (M2), Grashof number (G), Hall current parameter (m), rotational parameter (K2), magnetic field inclination (&#920), and the electrical conductance ratios of the upper (&#9201) and lower (&#9202) plates. Solutions are derived using the method of complex variables. Asymptotic solutions are also presented for very high rotation parameter and Hartmann number of order equal to unity, for which Ekman-Hartmann boundary layers are identified at the plates. A parametric study of the evolution of velocity and induced magnetic field distributions is undertaken. It is shown that generally increasing Hall current effect (m) serves to accentuate the secondary (cross) flow but oppose the primary flow. An increase in rotational parameter (K2) is also found to counteract primary flow intensity. An elevation in the Grashof number i.e. free convection parameter (G) is shown to aid the secondary induced magnetic field component (Hz); however there is a decrease in magnitudes of the primary induced magnetic field component (Hx) with increasing Grashof number. Increasing inclination of the applied magnetic field (&#920, is also found to oppose the primary flow (u1) but conversely to strongly assist the secondary flow (w1). Both critical primary (Gcx) and secondary (Gcz)Grashof numbers are shown to be reduced with increasing inclination of the magnetic field (&#920), increasing Hall parameter (m) and rotational parameter (K2). Applications of the study arise in rotating MHD induction power generators and also astrophysical flows.

Hydromagnetic Free Convective Rivlin - Ericksen Flow through a Porous Medium with Variable Permeability

Hydromagnetic Free Convective Rivlin - Ericksen Flow through a Porous Medium with Variable Permeability

On hydromagnetic free convection in the presence of induced magnetic field

Free convection in an electrically conducting fluid in a vertical channel under the action of an applied magnetic field has been discussed. The induced magnetic field has been included in the flow analysis. The equations describing the transport processes have been solved numerically. The effects of these processes, parameterized by a number of non-dimensional parameters have been discussed on the developing velocity and induced magnetic field profiles.

Hydromagnetic free convection currents effects on boundary layer thickness

Abstract In this study we discuss an unsteady free convection MHD flow past semi-infinite vertical porous plate. We have considered the flow in the presence of a strong magnetic field and therefore the electromagnetic force is very large. This brings in the phenomenon of Hall and Ion-slip currents. The effects of these two parameters together with that of viscous dissipation and radiation absorption among others on velocity, temperature and concentration profiles are presented. The profiles are presented graphically. As the partial differential equations governing this problem are highly non-linear they are solved numerically by a finite difference method. It is found that in presence of heating of the plate by free convection current the velocity boundary layer thickness decreases.

Modeling of unsteady MHD free convection flow with radiative heat transfer in a rotating fluid

In this paper, a numerical simulation has been carried out on unsteady hydromagnetic free convection near a moving infinite flat plate in a rotating medium. The temperatures involved are assumed to be very high so that the radiative heat transfer is significant, which renders the problem highly non-linear even with the assumption of a differential approximation for the radiative heat flux. A numerical method based on the Nakamura scheme has been employed to obtain the temperature and velocity distributions which are depicted graphically. The effects of the different parameters entering into the problem have been discussed extensively.

Hydromagnetic free convection of a radiating fluid

Natural convection of an electrically conducting and radiating fluid in the presence of an external magnetic field is investigated numerically. The two opposing side walls are differentially heated with a temperature difference specified, while the top and bottom walls are insulated. The coupled momentum and energy equations associating with the electromagnetic retarding force as well as the buoyancy force terms are solved by an iterative procedure using the SIMPLER algorithm based on control volume approach. Steady-state conditions are assumed. The finite-volume method is utilised to solve the radiation transport adopting the same computational grid as used in solving the flow field, with which the radiating fluids in an enclosure are assumed to be radiatively opaque, transparent and participating, respectively. After validating the numerical procedures, the changes in the buoyant flow patterns and temperature distribution affected by combined radiation and a magnetic field are focused mainly. Comparative results for the velocity profiles and the heat transfer rates are presented too. Based on the results of this study, it was found that the radiation played a significant role in developing the hydromagnetic free convective flow in a differentially heated enclosure.

Heat and mass transfer in the unsteady hydromagnetic free-convection flow in a rotating binary fluid II

Heat and mass transfer in the unsteady hydromagnetic free-convection flow in a rotating binary fluid II

Free convection heat and mass transfer with Hall current, Joule heating and thermal diffusion

A boundary layer analysis has been presented to study the combined effects of viscous dissipation, Joule heating, transpiration, heat source, thermal diffusion and Hall current on the hydromagnetic free convection and mass transfer flow of an electrically conducting, viscous, homogeneous, incompressible fluid past an infinite vertical porous plate. The governing partial differential equations of the hydromagnetic free convective boundary layer flow are reduced to non-linear ordinary differential equations and solutions for primary velocity, secondary velocity, temperature and concentration field are obtained for large suction. The expressions for the skin-friction, the heat transfer and the mass transfer are also derived. The results of the study are discussed through graphs and tables for different numerical values of the parameters entered into the equations governing the flow.

Hydromagnetic free convection flow with induced magnetic field effects

An exact solution is presented for the hydromagnetic natural convection boundary layer flow past an infinite vertical flat plate under the influence of a transverse magnetic field with magnetic induction effects included. The transformed ordinary differential equations are solved exactly, under physically appropriate boundary conditions. Closed-form expressions are obtained for the non-dimensional velocity (u), non-dimensional induced magnetic field component (B x ) and wall frictional shearing stress i.e. skin friction function (τ x ) as functions of dimensionless transverse coordinate (η), Grashof free convection number (G r ) and the Hartmann number (M). The bulk temperature in the boundary layer (Θ) is also evaluated and shown to be purely a function of M. The Rayleigh flow distribution (R) is derived and found to be a function of both Hartmann number (M) and the buoyant diffusivity parameter (ϑ *). The influence of Grashof number on velocity, induced magnetic field and wall shear stress profiles is computed. The response of Rayleigh flow distribution to Grashof numbers ranging from 2 to 200 is also discussed as is the influence of Hartmann number on the bulk temperature. Rayleigh flow is demonstrated to become stable with respect to the width of the boundary layer region and intensifies with greater magnetic field i.e. larger Hartman number M, for constant buoyant diffusivity parameter ϑ *. The induced magnetic field (B x ), is elevated in the vicinity of the plate surface with a rise in free convection (buoyancy) parameter G r , but is reduced over the central zone of the boundary layer regime. Applications of the study include laminar magneto-aerodynamics, materials processing and MHD propulsion thermo-fluid dynamics.

Thermal Radiation Effects on MHD Free Convection Flow Past an Impulsively Started Vertical Plate with Variable Surface Temperature and Concentration

Thermal radiation effects on hydromagnetic free convection flow past an impulsively started vertical plate with variable surface temperature and concentration is analyzed, by taking into account the heat due to viscous dissipation. The governing boundary layer equations of the flow field are solved by an implicit finite difference method of Crank-Nicholson type. A parametric study is performed to illustrate the influence of radiation parameter, magnetic parameter, Grashof number, Prandtl number, Eckert number on the velocity, temperature and concentration profiles. Also, the local and average skin-friction coefficient, Nusselt number and Sherwood number are presented graphically. The numerical results reveal that an increase in thermal radiation reduces both the velocity and temperature in the boundary layer and a rise in viscous dissipation accelerates the flow. Key words: Thermal radiation, MHD, viscous dissipation, vertical plate. DOI: 10.3329/jname.v5i2.2694 Journal of Naval Architecture and Marine Engineering 5(2)(2008) 57-70

Influence of chemical reaction and thermal radiation on the heat and mass transfer in MHD micropolar flow over a vertical moving porous plate in a porous medium with heat generation

An analysis is presented for the effects of chemical reaction and thermal radiation on hydromagnetic free convection heat and mass transfer for a micropolar fluid via a porous medium bounded by a semi-infinite vertical porous plate in the presence of heat generation. The plate moves with a constant velocity in the longitudinal direction and the free stream velocity follows an exponentially small perturbation law. A uniform magnetic field acts perpendicularly to the porous surface in which absorbs the micropolar fluid with a suction velocity varying with time. Analytical expressions are computed numerically. Numerical calculations are carried out the purpose of the discussion of the results which are shown on graphs and the effects of the various dimensionless parameters entering into the problem on the velocity, angular velocity, temperature, concentration. Also, the results of the skin-friction coefficient, the couple stress coefficient and the rates of the heat and mass transfers at the wall are prepared with various values of fluid properties and the flow conditions are studied.

Heat and mass transfer in the unsteady hydromagnetic free-convection flow in a rotating binary fluid I

The paper studies the unsteady free-convection flow near a moving infinite flat plate in a rotating binary mixture of an incompressible fluid. Both Soret (thermal diffusion), Dufour (diffusion-thermo) and radiation effects are considered when there is no chemical reaction. By imposing a time dependent perturbation on the constant plate temperature and concentration and assuming a differential approximation for the radiative flux, the coupled non linear problem is solved for the temperature and the concentration. First a critical value for the Soret was determined as 0.10 and the effects of Dufour, Soret and radiation show that while both Dufour and Soret have no effect on the temperature field, they both affect the concentration field with the Dufour causing an overwhelming increase and the Soret just a slight decrease. Furthermore radiation decreases both the temperature and concentration field. JONAMP Vol. 11 2007: pp. 533-543

Combined heat and mass transfer in magneto‐micropolar fluid flow from radiate surface with variable permeability in slip‐flow regime

AbstractAn analysis is presented to study the effects of radiation on the hydromagnetic free convection flow (set up due to temperature as well as species concentration) of an electrically conducting micropolar fluid past a vertical porous plate through porous medium in slip‐flow regime. A uniform magnetic field acts perpendiculary to the porous surface which absorbs the micropolar fluid with variable suction velocity. The Rosseland approximation is used to describe the radiative heat flux in energy equation. The numerical results of velocity distribution of micropolar fluids are compared with the corresponding flow problems for a Newtonian fluid. Assuming variable permeability of the medium, numerical results are presented graphically in the form of velocity, micro rotation, and temperature profiles for different material parameters entering into the analysis. Also, the results of the skin‐friction coefficient, the couple stress coefficient, the rate of heat and mass transfers at the wall are discussed with the help of figures.

Chebyshev Finite Difference Method for Hydro magnetic Free Convection from a Cone and a Wedge Through Porous Media with Radiation

Chebyshev Finite Difference Method for Hydro magnetic Free Convection from a Cone and a Wedge Through Porous Media with Radiation

ERRATUM: Chebyshev Finite Difference Method for Hydromagnetic Free Convection from a Cone and a Wedge Through Porous Media with Radiation by M.A. Seddeek was published in Volume 10, Issue 1, pages 99-108 of Journal of Porous Media

ERRATUM: Chebyshev Finite Difference Method for Hydromagnetic Free Convection from a Cone and a Wedge Through Porous Media with Radiation by M.A. Seddeek was published in Volume 10, Issue 1, pages 99-108 of Journal of Porous Media

Transient radiative hydromagnetic free convection flow past an impulsively started vertical plate with uniform heat and mass flux

The interaction of free convection with thermal radiation of viscous incompressible MHD unsteady flow past an impulsively started vertical plate with uniform heat and mass flux is analyzed. This type of problem finds application in many technological and engineering fields such as rocket propulsion systems, space craft re-entry aerothermodynamics, cosmical flight aerodynamics, plasma physics, glass production and furnace engineering .The Rosseland approximation is used to describe the radiative heat transfer in the limit of the optically thin fluid. The non-linear, coupled equations are solved using an implicit finite difference scheme of Crank-Nicolson type. Velocity, temperature and concentration of the flow have been presented for various parameters such as thermal Grashof number, mass Grashof number, Prandtl number, Schmidt number, radiation parameter and magnetic parameter. The local and average skin friction, Nusslet number and Sherwood number are also presented graphically. It is observed that, when the radiation parameter increases the velocity and temperature decrease in the boundary layer. .

Hydromagnetic free convection of a particulate suspension from a permeable inclined plate with heat absorption for non-uniform particle-phase density

The problem of steady, laminar, free convection flow of a particulate suspension over an infinite, permeable, inclined, and isothermal flat plate in the presence of a transverse magnetic field and fluid heat absorption effects is studied numerically. The problem accounts for particulate viscous effects which are absent from most two-phase models. An analytical solution is developed for the particle-phase density distribution and numerical solutions for the velocity and temperature profiles of both phases are obtained by using an implicit and iterative finite-difference method. A parametric study illustrating the influence of the magnetic field, heat absorption effects and particle loading is conducted. The obtained results for velocity, temperature and skin-friction coefficients for both phases as well as the Nusselt number are illustrated graphically to show the features of the solution.

MHD oscillatory flow on free convection–radiation through a porous medium with constant suction velocity

Unsteady two-dimensional hydromagnetic free convection and thermal radiation flow of an electrically conducting viscous-incompressible fluid, through a highly porous medium bounded by a vertical plane surface of constant temperature are presented. The Rosseland diffusion approximation is used to describe the radiative heat flux in the energy equation. Expressions for the velocity and temperature are obtained. The free-stream velocity of the fluid vibrates about a mean constant value and the surface absorbs the fluid with constant velocity. Effects of varying R (radiative parameter), G (Grashof number), k′ (permeability of the porous medium) and M (magnetic parameter upon the velocity field and the effect of varying R and Pr (Prandtl number) on the temperature are discussed.