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1.
The steady mixed convection flow over a vertical wedge with a magnetic field embedded in a porous medium has been investigated.
The effects of the permeability of the medium, surface mass transfer and viscous dissipation on the flow and temperature fields
have been included in the analysis. The coupled nonlinear partial differential equations governing the flow field have been
solved numerically using the Keller box method. The skin friction and heat transfer are found to increase with the parameters
characterizing the permeability of the medium, buoyancy force, magnetic field and pressure gradient. However the effect of
the permeability and magnetic field on the heat transfer is very small. The heat transfer increases with the Prandtl number,
but the skin friction decreases. The buoyancy force which assists the forced convection flow causes an overshoot in the velocity
profiles. Both the skin friction and heat transfer increase with suction and the effect of injection is just the reverse.
Received on 21 May 1999 相似文献
2.
The steady nonlinear hydromagnetic flow of an incompressible, viscous and electrically conducting fluid with heat transfer over a surface of variable temperature stretching with a power-law velocity in the presence of variable transverse magnetic field is analysed. Utilizing similarity transformation, governing nonlinear partial differential equations are transformed to nonlinear ordinary differential equations and they are numerically solved using fourth-order Runge–Kutta shooting method. Numerical solutions are illustrated graphically by means of graphs. The effects of magnetic field, stretching parameter and Prandtl number on velocity, skin friction, temperature distribution and rate of heat transfer are discussed. 相似文献
3.
Natural convection boundary layer flow over a continuously moving isothermal vertical surface immersed in a thermally stratified
medium has been investigated here. The non-linear coupled partial differential equations governing the non-similar flow have
been solved numerically using an implicit finite difference scheme. For small values of the streamwise distance the partial
differential equations are solved by using a perturbation expansion procedure and also using the Shanks transformation. The
results indicate that the thermal stratification significantly affects both the surface shear stress and the surface heat
transfer. The buoyancy parameter and the Prandtl number increase significantly, both the surface shear stress and heat transfer.
Also the buoyancy force gives rise to an overshoot in the velocity profile.
Received on 1 February 2000 相似文献
4.
Unsteady laminar mixed convection flow (combined free and forced convection flow) along a vertical slender cylinder embedded in a porous medium under the combined buoyancy effect of thermal and species diffusion has been studied. The effect of the permeability of the medium as well as the magnetic field has been included in the analysis. The partial differential equations with three independent variables governing the flow have been solved numerically using a implicit finite difference scheme in combination with the quasilinearization technique. Computations have been carried out for accelerating, decelerating and oscillatory free stream velocity distributions. The effects of the permeability of the medium, buoyancy forces, transverse curvature and magnetic field on skin friction, heat transfer and mass transfer have been studied. It is found that the effect of free stream velocity distribution is more pronounced on the skin friction than on the heat and mass transfer. The permeability and magnetic parameters increase the skin friction, but reduce the heat and mass transfer. The skin friction, heat transfer and mass transfer are enhanced due to the buoyancy forces and curvature parameter. The heat transfer is strongly dependent on the viscous dissipation parameter and the Prandtl number, and the mass transfer on the Schmidt number. 相似文献
5.
The mixed convection flow over a continuous moving vertical slender cylinder under the combined buoyancy effect of thermal
and mass diffusion has been studied. Both uniform wall temperature (concentration) and uniform heat (mass) flux cases are
included in the analysis. The problem is formulated in such a manner that when the ratio λ(= u
w/(u
w + u
∞), where u
w and u
∞ are the wall and free stream velocities, is zero, the problem reduces to the flow over a stationary cylinder, and when λ = 1
it reduces to the flow over a moving cylinder in an ambient fluid. The partial differential equations governing the flow have
been solved numerically using an implicit finite-difference scheme. We have also obtained the solution using a perturbation
technique with Shanks transformation. This transformation has been used to increase the range of the validity of the solution.
For some particular cases closed form solutions are obtained. The surface skin friction, heat transfer and mass transfer increase
with the buoyancy forces. The buoyancy forces cause considerable overshoot in the velocity profiles. The Prandtl number and
the Schmidt number strongly affect the surface heat transfer and the mass transfer, respectively. The surface skin friction
decreases as the relative velocity between the surface and free stream decreases.
Received on 17 May 1999 相似文献
6.
In the present work, the effect of MHD flow and heat transfer within a boundary layer flow on an upper-convected Maxwell (UCM)
fluid over a stretching sheet is examined. The governing boundary layer equations of motion and heat transfer are non-dimensionalized
using suitable similarity variables and the resulting transformed, ordinary differential equations are then solved numerically
by shooting technique with fourth order Runge–Kutta method. For a UCM fluid, a thinning of the boundary layer and a drop in
wall skin friction coefficient is predicted to occur for higher the elastic number. The objective of the present work is to
investigate the effect of Maxwell parameter β, magnetic parameter Mn and Prandtl number Pr on the temperature field above the sheet. 相似文献
7.
The unsteady free convection flow over an infinite vertical porous plate, which moves with time-dependent velocity in an ambient fluid, has been studied. The effects of the magnetic field and Hall current are included in the analysis. The buoyancy forces arise due to both the thermal and mass diffusion. The partial differential equations governing the flow have been solved numerically using both the implicit finite difference scheme and the difference-differential method. For the steady case, analytical solutions have also been obtained. The effect of time variation on the skin friction, heat transfer and mass transfer is very significant. Suction increases the skin friction coefficient in the primary flow, and also the Nusselt and Sherwood numbers, but the skin friction coefficient in the secondary flow is reduced. The effect of injection is opposite to that of suction. The buoyancy force, injection and the Hall parameter induce an overshoot in the velocity profiles in the primary flow which changes the velocity gradient from a negative to a positive value, but the magnetic field and suction reduce this velocity overshoot. 相似文献
8.
K. Das 《Heat and Mass Transfer》2012,48(5):767-778
The influence of partial slip, thermal radiation and temperature dependent fluid properties on the hydro-magnetic fluid flow
and heat transfer over a flat plate with convective surface heat flux at the boundary and non-uniform heat source/sink is
studied. The transverse magnetic field is assumed as a function of the distance from the origin. Also it is assumed that the
fluid viscosity and the thermal conductivity vary as an inverse function and linear function of temperature respectively.
Using the similarity transformation, the governing system of non-linear partial differential equations are transformed into
similarity non-linear ordinary differential equations and are solved numerically using symbolic software MATHEMATICA 7.0.
The numerical values obtained within the boundary layer for the dimensionless velocity, temperature, skin friction coefficient
and the Nusselt number are presented through graphs and tables for several sets of values of the parameters. The effects of
various physical parameters on the flow and heat transfer characteristics are discussed from the physical point of view. 相似文献
9.
In this paper, the problem of free convection boundary layer flow on a solid sphere in a micropolar fluid with Newtonian heating,
in which the heat transfer from the surface is proportional to the local surface temperature, is considered. The transformed
boundary layer equations in the form of partial differential equations are solved numerically using an implicit finite-difference
scheme. Numerical solutions are obtained for the local wall temperature, the local skin friction coefficient, as well as the
velocity, angular velocity and temperature profiles. The features of the flow and heat transfer characteristics for different
values of the material or micropolar parameter K, the Prandtl number Pr and the conjugate parameter γ are analyzed and discussed. 相似文献
10.
A boundary layer analysis is performed to study the influence of thermal radiation and buoyancy force on two-dimensional magnetohydrodynamic
flow of an incompressible viscous and electrically conducting fluid over a vertical stretching sheet embedded in a porous
medium in the presence of inertia effect. The governing system of partial differential equations is first transformed into
system of ordinary differential equations using self-similarity transformation. A special form for magnetic field is chosen
to obtain the similarity solution. The transformed boundary layer equations are solved numerically for some important values
of the physical parameters. The present results are compared with the previously published papers and the results are found
to be in excellent agreement. The important features of the flow, heat and mass transfer characteristics for different values
of thermal radiation, porous permeability, magnetic field and buoyancy parameters are analyzed and discussed. The effects
of various physical parameters on the skin friction coefficient, local Nusselt number and local Sherwood number are also presented.
It is found that increase in the value of thermal radiation parameter R
1 increases the skin friction coefficient and Sherwood number whereas reverse trend is seen for the local Nusselt number. 相似文献
11.
K. Das 《国际流体数值方法杂志》2012,70(1):96-113
The influence of partial slip, thermal radiation, chemical reaction and temperature‐dependent fluid properties on heat and mass transfer in hydro‐magnetic micropolar fluid flow over an inclined permeable plate with constant heat flux and non‐uniform heat source/sink is studied. The transverse magnetic field is assumed as a function of the distance from the origin. Also it is assumed that the fluid viscosity and the thermal conductivity vary as an inverse function and linear function of temperature, respectively. With the use of the similarity transformation, the governing system of non‐linear partial differential equations are transformed into non‐linear ordinary differential equations and are solved numerically using symbolic software MATHEMATICA 7.0 (Wolfram Research, Champaign, IL). The numerical values obtained for the velocity, microrotation, temperature, species concentration, skin friction coefficient and the Nusselt number are presented through graphs and tables for several sets of values of the parameters. The effects of various physical parameters on the flow and heat transfer characteristics are discussed.Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
12.
The steady laminar boundary layer flow and heat transfer from a warm, laminar liquid flow to a melting surface moving parallel
to a constant free stream is studied in this paper. The continuity, momentum and energy equations, which are coupled nonlinear
partial differential equations are reduced to a set of two nonlinear ordinary differential equations, before being solved
numerically using the Runge–Kutta–Fehlberg method. Results for the skin friction coefficient, local Nusselt number, velocity
profiles as well as temperature profiles are presented for different values of the governing parameters. Effects of the melting
parameter, moving parameter and Prandtl number on the flow and heat transfer characteristics are thoroughly examined. It is
found that the problem admits dual solutions. 相似文献
13.
Mixed convection heat transfer about a semi-infinite inclined plate in the presence of magneto and thermal radiation effects
is studied. The fluid is assumed to be incompressible and dense. The nonlinear coupled parabolic partial differential equations
governing the flow are transformed into the non-similar boundary layer equations, which are then solved numerically using
the Keller box method. The effects of the mixed convection parameter R
i, the angle of inclination α, the magnetic parameter M and the radiation–conduction parameter R
d on the velocity and temperature profiles as well as on the local skin friction and local heat transfer parameters. For some
specific values of the governing parameters, the results are compared with those available in the literature and a fairly
good agreement is obtained. 相似文献
14.
Mohamed Abd El-Aziz 《Meccanica》2010,45(1):97-109
The present investigation is concerned with the effect of Hall currents on the flow and heat transfer of an electrically conducting
fluid over an unsteady stretching surface in presence of a strong magnetic field. The induced magnetic field is neglected
while the electron-atom collision frequency is assumed to be relatively high, so that the Hall effect is assumed to exist.
The incorrect similarity transformation of Elbashbeshy and Bazid (Heat Mass Transfer 41:1–4, 2004). is corrected and a physically realistic distribution of the velocity and temperature is obtained. Using a similarity transformation
the governing time dependent boundary layer equations for momentum and thermal energy are reduced to a set of coupled ordinary
differential equations which are then solved numerically by the shooting method. Effects of the magnetic field, M , Hall parameter, m, and the unsteadiness parameter, S, on the velocity and temperature profiles as well as the local skin friction coefficients and the heat transfer rate are
shown graphically. 相似文献
15.
A. S. Butt M. N. Tufail Asif Ali 《Journal of Applied Mechanics and Technical Physics》2016,57(2):283-292
A three-dimensional flow of a magnetohydrodynamic Casson fluid over an unsteady stretching surface placed into a porous medium is examined. Similarity transformations are used to convert time-dependent partial differential equations into nonlinear ordinary differential equations. The transformed equations are then solved analytically by the homotopy analysis method and numerically by the shooting technique combined with the Runge–Kutta–Fehlberg method. The results obtained by both methods are compared with available reported data. The effects of the Casson fluid parameter, magnetic field parameter, and unsteadiness parameter on the velocity and local skin friction coefficients are discussed in detail. 相似文献
16.
The steady mixed convection flow and heat transfer from an exponentially stretching vertical surface in a quiescent Maxwell fluid in the presence of magnetic field, viscous dissipation and Joule heating have been studied. The stretching velocity, surface temperature and magnetic field are assumed to have specific exponential function forms for the existence of the local similarity solution. The coupled nonlinear ordinary differential equations governing the local similarity flow and heat transfer have been solved numerically by Chebyshev finite difference method. The influence of the buoyancy parameter, viscous dissipation, relaxation parameter of Maxwell fluid, magnetic field and Prandtl number on the flow and heat transfer has been considered in detail. The Nusselt number increases significantly with the Prandtl number, but the skin friction coefficient decreases. The Nusselt number slightly decreases with increasing viscous dissipation parameter, but the skin friction coefficient slightly increases. Maxwell fluid reduces both skin friction coefficient and Nusselt number, whereas buoyancy force enhances them. 相似文献
17.
An analysis is made for the steady two-dimensional magneto-hydrodynamic flow of an incompressible viscous and electrically
conducting fluid over a stretching vertical sheet in its own plane. The stretching velocity, the surface temperature and the
transverse magnetic field are assumed to vary in a power-law with the distance from the origin. The transformed boundary layer
equations are solved numerically for some values of the involved parameters, namely the magnetic parameter M, the velocity exponent parameter m, the temperature exponent parameter n and the buoyancy parameter λ, while the Prandtl number Pr is fixed, namely Pr = 1, using a finite difference scheme known as the Keller-box method. Similarity solutions are obtained in the presence of
the buoyancy force if n = 2m−1. The features of the flow and heat transfer characteristics for different values of the governing parameters are analyzed
and discussed. It is found that both the skin friction coefficient and the local Nusselt number decrease as the magnetic parameter
M increases for fixed λ and m. For m = 0.2 (i.e. n = −0.6), although the sheet and the fluid are at different temperatures, there is no local heat transfer at the surface of
the sheet except at the singular point of the origin (fixed point). 相似文献
18.
Unsteady flow over an infinite permeable rotating cone in a rotating fluid in the presence of an applied magnetic field has been investigated. The unsteadiness is induced by the time-dependent angular velocity of the body, as well as that of the fluid. The partial differential equations governing the flow have been solved numerically by using an implicit finite-difference scheme in combination with the quasi-linearization technique. For large values of the magnetic parameter, analytical solutions have also been obtained for the steady-state case. It is observed that the magnetic field, surface velocity, and suction and injection strongly affect the local skin friction coefficients in the tangential and azimuthal directions. The local skin friction coefficients increase when the angular velocity of the fluid or body increases with time, but these decrease with decreasing angular velocity. The skin friction coefficients in the tangential and azimuthal directions vanish when the angular velocities of fluid and the body are equal but this does not imply separation. When the angular velocity of the fluid is greater than that of the body, the velocity profiles reach their asymptotic values at the edge of the boundary layer in an oscillatory manner, but the magnetic field or suction reduces or suppresses these oscillations. 相似文献
19.
Emad M. Abo-Eldahab 《Heat and Mass Transfer》2005,41(8):734-743
A general analysis has been developed to study the combined effect of the free convective heat and mass transfer on the steady three-dimensional laminar boundary layer flow over a stretching surface. The flow is subject to a transverse magnetic field normal to the plate. The governing three-dimensional partial differential equations for the present case are transformed into ordinary differential equation using three-dimensional similarity variables. The resulting equations, are solved numerically by applying a fifth order Runge-Kutta-Fehlberg scheme with 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 distributions. Numerical data for the skin-friction coefficients, Nusselt and Sherwood numbers have been tabulated for various parametric conditions. The results are compared with known from the literature. 相似文献
20.
An analysis is developed to study the unsteady mixed convection flow over a vertical cone rotating in an ambient fluid with a time-dependent angular velocity in the presence of a magnetic field. The coupled nonlinear partial differential equations governing the flow have been solved numerically using an implicit finite-difference scheme. The local skin friction coefficients in the tangential and azimuthal directions and the local Nusselt number increase with the time when the angular velocity of the cone increases, but the reverse trend is observed for decreasing angular velocity. However, these are not mirror reflection of each other. The magnetic field reduces the skin friction coefficient in the tangential direction and also the Nusselt number, but it increases the skin friction coefficient in the azimuthal direction. The skin friction coefficients and the Nusselt number increase with the buoyancy force. 相似文献