Effects of mass transfer and free convection on the unsteady mhd flow past a vertical porous plate with variable suction

In this paper we investigate the effects of mass transfer on the unsteady free convective flow of an electrically conducting and viscous incompressible fluid past an infinite vertical plate subjected to variable suction, in the presence of transverse magnetic field, when the free-stream velocity oscillates with time in magnitude but not in direction. In this analysis, the effects of the induced magnetic field is neglected. Approximate solutions to the transient flow, the amplitude and phase of skin-friction and the rate of heat transfer have been derived. During the course of the discussion, the effects of Gr, Gc, Sc, Ec, M and ω have been presented.     

Effects of mass transfer and free convection on the unsteady mhd flow past a vertical porous plate with constant suction

Effects of free convection currents and mass transfer on the unsteady flow of an electrically conducting and viscous incompressible fluid past an infinite vertical porous plate subjected to uniform suction, in the presence of transverse magnetic field, have been studied taking into account that the external flow velocity varies periodically with time in magnitude but not in direction. The effect of the induced magnetic field has been neglected. Approximate solutions to the transient flow, the amplitude and the phase of the skin-friction and the rate of heat transfer have been derived. During the course of the discussion, the effects of the Grashoff number Gr, the modified Grashoff number Gc (depending on the concentration difference), the Schmidt number Sc, the Eckert number Ec, the magnetic field parameter M, and the frequency ω have been discussed.     

Mass transfer and free convection flow through A porous medium

A theoretical analysis of the steady free convective and mass transfer flow is presented, when a viscous and incompressible fluid flows through a porous medium occupying a semi-infinite region of the space bounded by an infinite vertical porous plate. The fluid is subjected to a normal suction velocity, and the heat flux at the plate is constant. The free-stream velocity is assumed constant.     

Free convection heat and mass transfer to steady flow in a semi-infinite vertical porous medium

Analytical solutions are derived for flow in a semi-infinite vertical porous medium with heat and mass transfer. When the temperature and mass concentration are uniform a constant pressure is possible and sustains a fully developed flow. Thereafter there is a small perturbation of the wall temperature and concentration, and the subsequent two-dimensional problem is tackled for large Prandtl number and free convection parameters and small Reynolds number. The heat transfer rate at the wall is discussed quantitatively.     

Oscillatory flow in a stratified medium past an infinite porous plate with constant suction

An approximate solution to oscillatory flow past a porous horizontal plate was carried out under the following conditions

• (i) Constant suction
• (ii) Stratification of the medium due to change in density, viscosity and thermal conductivity
• (iii) Free-stream oscillation about a nonzero constant mean.

Solutions have been derived for the transient velocity, the transient temperature, the amplitude and the phase of skin friction and the amplitude and phase of the first and second harmonics of the rate of heat transfer. These are shown on the graphs. The effects of the suction parameter S, the stratification parameter λ, the frequency λ and the Eckert number E are discussed.     

Hall effects on the hydromagnetic free convective flow and mass transfer through a porous medium bounded by an infinite vertical porous plate with constant heat flux

Effects of Hall current on free convection and mass transfer flow through a porous medium bounded by a vertical surface when a uniform magnetic field acts in a plane which makes an angle x with the plane transverse to the plate have been analysed. An analytic solution of the problem is obtained and the effects of the Hall parameter and the permeability parameter, as well as the other parameters entering into the problem, are discussed and shown graphically.     

Radiation effect on MHD flow past a porous vertical plate in the presence of heat sink

This study investigates heat and mass transfer in MHD convective flow through a vertical plate via porous media in the presence of radiation and a heat source/sink. It is assumed that a uniform magnetic field of strength is imposed perpendicular to the plate and directed into the fluid area. The governing nondimensional equations are solved using the perturbation technique. We further derived the skin friction, Nusselt number, and Sherwood number. The computation of results is performed with the aid of mathematical software and results are presented in graphical and tabular forms for distinct flow impacting parameters. It is observed that fluid motion is retarded due to the application of the magnetic field. Furthermore, the fluid temperature comprehensively falls under the Prandtl number as well as the thermal radiation effect. It is important to note that the heat sink causes fluid velocity and fluid temperature to fall drastically.     

A note on heat transfer to MHD oscillatory flow in an asymmetric wavy channel

This note deals with the MHD oscillatory flow of an optically thin fluid in an asymmetric wavy channel filled with porous medium. Based on some simplifying assumptions, the governing momentum and energy equations are solved and analytical solutions for fluid velocity, temperature distribution, Nusselt number and skin friction are constructed. The effects of radiation parameter, Peclet number, Hartmann number, porous medium shape factor and geometric parameters on flow and heat transfer characteristics have been examined in detail.     

Analysis of MHD micropolar nanofluid flow and heat transfer between a porous plate and a nonporous plate filled with porous medium

This article presents an analytical study on magnetohydrodynamic micropolar nanofluid flow through parallel, coaxial discs filled with a porous medium with uniform blowing from the upper plate. Three different types of nanoparticles, namely copper, aluminum oxide, and titanium dioxide are considered with water and used as base fluids. The governing equations are solved via Differential Transformation Method. The validity of this method has been verified with the results of numerical solution (fourth‐order Runge‐Kutta scheme). The analytical investigation is carried out for different governing parameters. The results indicate that skin friction coefficient has a direct relationship with Hartmann number and the micropolar parameter. It is also found that Nusselt number is increased with increment in Prandtl number and Eckert number. Additionally, this analysis concluded that an increase in volume fraction of nanofluid increases the Nusselt number on the top plate and decreases it on the lower plate.     

MHD effect on flow structures and heat transfer characteristics of liquid metal-gas annular flow in a vertical pipe

The magnetohydrodynamic (MHD) effect on the flow structures and heat transfer characteristics was studied numerically for a liquid metal-gas annular flow under a transverse magnetic field. The side layers, in which the velocity was increased, appeared near the eastern and western sidewalls in an annular MHD flow as in a single-phase liquid metal MHD flow. Temperature distribution in the liquid film, and the Nusselt number distribution in the angular direction were influenced by the flow structures with the side layers. Consequently heat transfer rate was higher at the eastern/western sidewalls than that at the southern/northern walls. The pressure drop in the MHD annular flow is of the same order of magnitude as in the single-phase MHD pipe flow under similar liquid metal flow condition.     

Natural convection MHD mass transfer through an infinite vertical porous plate in the existence of radiation embedded in porous medium

This research focuses on studying the effects of heat and mass transfer convective flow passing through an infinite vertical plate embedded in porous media under radiation and chemical reaction with constant heat and mass flux. A magnetic field of strength is functional throughout the fluid region. The novelty of the present work is to examine the heat and mass transfer magnetohydrodynamics flow in the presence of thermal radiation. The equations governing the flow, heat and mass transfer are solved analytically using the perturbation technique. Expressions for velocity, temperature, concentration, skin-friction, Nusselt, and Sherwood numbers are obtained. The influence of physical parameters on the flow domain is described graphically and in tabular form. It is found that increase in radiation parameter reduces the velocity and temperature. Moreover, internal friction of the plate decreased with increasing values of radiation parameter.     

MHD natural convection heat and mass transfer flow over an inclined porous plate with thermophoresis and nonlinear thermal radiation effects

This study examined magnetohydrodynamic natural convection mass and heat transfer flow of an electrically conducting and viscous incompressible fluid over an inclined porous plate with thermophoresis, suction/injection, and uniform magnetic field. The mathematical model governing the fluid behavior surrounding an inclined plate is solved through the Runge–Kutta–Fehlberg fourth–fifth order after utilizing the shooting method. The implication of active dimensionless parameters in the governing equations is fully discussed in detail. The results obtained show that, in the existence of nonlinear thermal radiation and suction/injection, the heat transfer rises with the increase in the angle of inclination but it decreases with the mass transfer and plate shear stress. Furthermore, the heat transfer rate experiences a serious setback due to the increase in the buoyancy force but improves the plate shear stress. The mass transfer is directly proportional to the thermophoresis effect. In addition, Particle suction increases the velocity and temperature curves while it declines the concentration profile, but the opposite is valid for injection. Nonlinear thermal radiation positively affects the temperature, velocity, and concentration profiles. The Lorentz force suppresses the fluid transport and retard the rate of particle concentration, but promotes the fluid temperature distribution. It is also deduced that increasing the rate of particle suction from 0 to 1, accounts for over 76% increase in the particle deposition at the plate surface. However, increasing the rate of particle injection from 0.004 to 0.250 accounts for an over 83% decrease in the particle deposition at the plate surface.     

MHD free convective dissipative flow past a porous plate in a porous medium in the presence of radiation and thermal diffusion effects

The problem of a hydromagnetic convective flow of an electrically incompressible viscous conducting fluid past a uniformly moving vertical porous plate is investigated analytically, taking into consideration radiation and thermal diffusion effects. A constant suction velocity is applied to the plate. A uniformly strong magnetic field is supposed to be applied normally to the plate and directed into the fluid region. To find a solution to the problem, an asymptotic series expansion method is used. The effects of thermal diffusion, magnetic field, porosity parameter, thermal radiation, and Grashof number are mainly focused on the discussion of the current problem. Increasing Soret number (Sr) hikes the velocity profile and skin friction but declines Sherwood number. Also, it has been found that, when the magnetic parameter (M) increased, the fluid velocity and the concentration profile decreased. The current results show a good deal of agreement with previously published work. The findings of this study could be relevant in a variety of applications, including diffusion processes involving molecular diffusion of species with molar concentration.     

MHD convective rotating flow of viscoelastic fluid past an infinite vertical oscillating porous plate with Hall effects

It is considered the unsteady and incompressible magnetohydrodynamic rotating free convection flow of viscoelastic fluid with simultaneous heat and mass transfer near an infinite vertical oscillating porous plate under the influence of uniform transverse magnetic field and taking Hall current into account. The governing equations of the flow field are then solved by a regular perturbation method for a small elastic parameter. The expressions for the velocity, temperature, and concentration have been derived analytically and also its behavior is computationally discussed with reference to different flow parameters with the help of graphs. The skin friction on the boundary, the heat flux in terms of the Nusselt number, and the rate of mass transfer in terms of the Sherwood number are also obtained and their behavior discussed. The resultant velocity enhances with increasing Hall parameter and rotation parameter. The reversal behavior is observed with increasing viscoelastic parameters. The resultant velocity enhances and experiences retardation in the flow field with increasing radiation parameters, whereas the secondary velocity component increases with increasing rotation parameters. The temperature diminishes as the Prandtl number and/or the frequency of oscillations. The concentration reduces at all points of the flow field with the increase in the Schmidt number.     

Effect of oscillatory motion on heat transfer at vertical flat surfaces

The effect of oscillations on heat transfer at vertical surfaces is investigated and a model is developed that predicted both the transient and time average heat transfer rates. The transient behavior of the heat transfer indicates the presence of an oscillatory component superimposed on a larger steady one that does not reach zero during flow reversal. This was explained in terms of the interaction between a “quasi-steady oscillatory” mechanism near the leading edge, and a “pseudo-steady diffusive” far from it. The analysis further revealed that the time average heat transfer rate can be adequately estimated using a mixed “forced-natural” convections correlation, with the forced convection component estimated based on the time average oscillatory Reynolds number Re_v = awL/ν. The agreement between the model predictions and the experimental measurements makes it applicable for predicting heat transfer characteristics and velocity fluctuations near heated vertical surfaces in presence of oscillatory motion. The model is also applicable for predicting heat transfer rates under conditions where oscillatory motion is used to achieve specificity in temperature control without affecting process residence time, such as in biomedical and biochemical applications. The modest heat transfer enhancement (<2) due to oscillatory motion is attributed to the small convective term in the energy equation, which is consistent with previous investigations where increasing the axial temperature gradient in presence of oscillatory motion was shown to achieve much higher heat transfer enhancement.     

Effects of chemical reaction, heat and mass transfer along a wedge with heat source and concentration in the presence of suction or injection

An approximate numerical solution for the steady laminar boundary-layer flow over a wall of the wedge with suction or injection in the presence of species concentration and mass diffusion has been obtained by solving the governing equations using numerical technique. The fluid is assumed to be viscous and incompressible. Numerical calculations up to third level of truncation are carried out for different values of dimensionless parameters and an analysis of the results obtained shows that the flow field is influenced appreciably by the chemical reaction, heat source and suction or injection at the wall of the wedge.     

Heat transfer in fluctuating flow past an infinite plate with suction and constant heat flux

An analysis of unsteady heat transfer in a two-dimensional flow past an infinite porous plate has been carried out under the following conditions: (1) constant or variable suction; (2) free-stream oscillating in time about a non-zero constant mean; and (3) constant heat flux at the plate. Approximate solutions to the temperature field have been derived. the transient temperature, the amplitude and phase of the Nusselt number are shown on graphs.     

Heat transfer in the magnetohydrodynamic flow of a power-law fluid past a porous flat plate with suction or blowing

An analysis is made of the steady magnetohydrodynamic flow of a power-law fluid past an infinite porous flat plate subjected to suction or blowing. A uniform transverse magnetic field is applied normal to the plate. It is shown that for small magnetic field parameter M, the steady solutions for velocity distribution exist for a pseudoplastic (shear-thinning) fluid for which the power-law index n satisfies 1/2 < n ≤ 1 provided that there is suction at the plate. For blowing at the plate the steady solutions for velocity distribution exist only when n is of the form p/q, where p is an odd positive integer and q is an even positive integer provided 1/2 < n < 1. Velocity at a point is found to increase with increase in M. The solution of the energy equation governing temperature distribution in the flow of a pseudoplastic fluid past an infinite porous plate subjected to uniform suction reveals that the temperature at a given point increases with increase in M.     

Effects of hall current and wall temperature oscillation on free convective and mass transfer flow in a rotating porous medium with constant heat source

The combined effects of Hall current and a constant heat source on the hydromagnetic free convective and mass transfer flow past an infinite vertical porous plate in a rotating porous medium are considered, when the temperature of the plate varies with time about a nonzero constant mean and the temperature of the free stream is constant. The problem is solved analytically and the velocity profiles are shown on graphs. Effects of m (Hall parameter) and α (heat source parameter) on velocity are discussed extensively.     

Heat and mass transfer on MHD convective flow over an infinite vertical porous plate with the heat source and chemical reaction

It is considered that the magnetohydrodynamic free convective flow of an incompressible electrically conducting fluid through a porous medium past a vertical absorbent surface. The homogeneous transverse magnetic field is considered in the existence of heat source and chemical reaction in the rotating frame. The accurate solutions of the velocity, temperature, and concentration are acquired systematically making use of the perturbation method. The consequences of a variety of governing flow parameters on the velocity, temperature, and concentration are analyzed through graphical profiles. Computational outcomes for the skin friction, Nusselt number, and Sherwood number through the tabular format were also examined.