M. Hasan et al.
by Ostrach [1]. Hossain and Takhar [2] analyzed the effect of radiation effects on
free convection flow of a gas past a semi infinite flat plate using the Cog-
ley-Vincnitine-Giles equilibrium model. Ali
et al.
[3] studied the radiation effect
on natural convection flow over a vertical surface in a gray gas. Following Ali
et
al.
, Mansour [4] studied the interaction of mixed convection with thermal radia-
tion in laminar boundary layer flow over a horizontal, continuous moving sheet
with suction/injection. Alabraba
et al.
[5] studied the same problem considering
magnetic effect taking into account the chemical reaction and soret-doufour ef-
fects. Sattar and Kalim [6] made a study of the combined unsteady free convec-
tion dynamic boundary layer and thermal radiation boundary layer on a
semi-infinite vertical plate by using the Rosseland diffusion approximation.
Chen [7] investigated natural convection flow over a permeable surface with va-
riable wall temperature and concentration.
The viscous dissipation effect plays an important role in natural convection.
Natural convection flow is often encountered in the cooling of nuclear reactors.
Viscous dissipation effects on non-linear MHD flow in a porous medium over a
stretching porous surface have been studied by S.P. Anjali Devi and B. Ganga
[8]. Jha and Ajibade [9] studied the effect of viscous dissipation on natural con-
vection flow between vertical parallel plates with time-periodic boundary condi-
tions. Ferdows
et al.
[10] described that in the presence of uniform magnetic
field with viscous dissipation at the wall, the thermophoretic parameter is one of
the most useful parameters to control the boundary layer of the fluid.
The analysis and discussion of natural convection flow, the viscous dissipation
effect is generally ignored but here considered the combined effect of viscous
dissipation and radiation on free convection flow an inclined stretching sheet.
2. Mathematical Analysis
A steady-state two-dimensional heat and mass transfer flow of an electrically
conducting viscous incompressible fluid along an isothermal stretching permea-
ble inclined sheet with an angle
to the vertical embedded in a porous me-
dium with heat generation/absorption is considered. A strong magnetic field is
applied in the
y-
axis direction. Here the effect of the induced magnetic field is
neglected in comparison to the applied magnetic field. The electrical current
flowing in the fluid gives rise to an induced magnetic field if the fluid were an
electrical insulator, but here we have taken the fluid to be electrically conducting.
Hence, only the applied magnetic field of strength
B
0
plays a role which gives rise
to magnetic forces
in
x
-direction,
where is the electrical con-
ductivity assumed to be directly proportional to the
x
- translational velocity (
u
)
of the fluid found by Helmy [11] and
is the density of the fluid. Two equal
and opposite forces are introduced along the
x
- axis so that the sheet is stretched
keeping the origin fixed as shown in
Figure 1.
The fluid is considered to be gray, absorbing emitting radiation but non-scat-
tering medium and the Rosseland approximation is used to describe the radia-
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