Abstract.
Magnetohydrodynamic natural convection heat transfer from radiate vertical surfaces with fluid suction or injection is considered. The nonsimilarity parameter is found to be the conductive fluid injection or suction along the streamwise coordinate ξ = V{4x/υ2 gβ(T w – T ∞)}1/4. Three dimensionless parameters had been found to describe the problem: the magnetic influence number N = σB 2 y υ/ρV 2, the radiation-conduction parameter R d = kα R /4aT 3 ∞, and the Gebhart number Ge x = gβx/cp to represent the effect of the viscous dissipation. It is found that increasing the magnetic field strength causes the velocity and the heat transfer rates inside the boundary layer to decrease. Its apparent that increasing the radiation-conduction parameter decreases the velocity and enhances the heat transfer rates. The Gebhart number, i.e, the viscous dissipation had no effect on the present problem.
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Abbreviations
- a :
-
Stefan-Boltzmann constant
- B y :
-
Magnetic field flux density Wb/m2
- Cf x :
-
Local skin friction factor
- c p :
-
Specific heat capacity
- f :
-
Dimensionless stream function
- Ge x :
-
Gebhart number, gβx/cp
- g :
-
Gravitational acceleration
- k :
-
Thermal Conductivity
- L :
-
Length of the plate
- N :
-
Magnetic influence number, σB 2 y υ/ρV 2
- p :
-
Pressure
- Pr :
-
Prandtl number
- q r :
-
Radiative heat flux
- q w (x):
-
Local surface heat flux
- Q w (x):
-
Dimensionless Local surface heat flux
- R d :
-
Planck number (Radiation-Conduction parameter), kα R /4aT 3 ∞
- T :
-
Temperature
- T ∞ :
-
Free stream temperature
- T w :
-
Wall temperature
- u, v :
-
Velocity components in x- and y-directions
- V :
-
Porous wall suction or injection velocity
- V w :
-
Porous wall suction or injection velocity
- x, y :
-
Axial and normal coordinates
- α:
-
Thermal diffusivity
- α R :
-
Roseland mean absorption coefficient, 4/3R d
- β:
-
Coefficient of thermal expansion
- ξ:
-
Nonsimilarity parameter, V{4x/υ2 gβ(T w – T ∞)}1/4
- η:
-
Peseudo-similarity variable
- θ:
-
Dimensionless temperature
- θ w :
-
Ratio of surface temperature to the ambient temperature, T w /T ∞
- μ:
-
Dynamice viscosity
- υ:
-
Kinemtic viscosity
- ρ:
-
Fluid density
- σ:
-
Electrical conductivity
- τ w :
-
Local wall shear stress
- ψ:
-
Dimensional stream function
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Duwairi, H.M., Damseh, R.A. Magnetohydrodynamic natural convection heat transfer from radiate vertical porous surfaces. Heat Mass Transfer 40, 787–792 (2004). https://doi.org/10.1007/s00231-003-0476-2
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DOI: https://doi.org/10.1007/s00231-003-0476-2