Abstract
The free convective heat transfer to the power-law non-Newtonian flow from a vertical plate in a porous medium saturated with nanofluid under laminar conditions is investigated. It is considered that the non-Newtonian nanofluid obeys the mathematical model of power-law. The model used for the nanofluid incorporates the effects of Brownian motion and thermophoresis. The partial differential system governing the problem is transformed into an ordinary system via a usual similarity transformation. The numerical solutions of the resulting ordinary system are obtained. These solutions depend on the power-law index n, Lewis number Le, buoyancy-ratio number N r, Brownian motion number N b, and thermophoresis number N t. For various values of n and Le, the effects of the influence parameters on the fluid behavior as well as the reduced Nusselt number are presented and discussed.
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Abbreviations
- D B :
-
Brownian diffusion coefficient
- D T :
-
thermophoretic diffusion coefficient
- f :
-
rescaled nanoparticle volume fraction
- g :
-
gravitational acceleration
- k m :
-
effective thermal conductivity
- K :
-
permeability of the porous medium
- Le :
-
Lewis number
- n :
-
power index of non-Newtonian fluid, n ⩾ 0
- N r :
-
buoyancy ratio
- N b :
-
Brownian parameter
- N t :
-
thermophoresis parameter
- Nu :
-
Nusselt number
- Nu r :
-
reduced Nusselt number, \(Nu/Ra_x^{\tfrac{1} {2}} \)
- q w :
-
wall heat flux
- Ra x :
-
modified Rayleigh number
- s :
-
dimensionless stream function
- T :
-
temperature
- T w :
-
temperature at the vertical plate
- T ∞ :
-
ambient temperature attained as y → ∞
- u, υ :
-
Darcian velocity components in x- and y-directions
- x, y :
-
Cartesian coordinates
- α m :
-
thermal diffusivity
- β :
-
volumetric expansion coefficient of the non-Newtonian fluid
- ɛ :
-
porosity
- η :
-
similarity variable
- θ :
-
dimensionless temperature
- μ :
-
effective viscosity of non-Newtonian fluid
- ρ f :
-
density of the non-Newtonian fluid
- ρ p :
-
nanoparticles mass density
- (ρc)f :
-
heat capacity of the fluid
- (ρc)m :
-
effective heat capacity of the porous medium
- (ρc)p :
-
effective heat capacity of the nanoparticles material
- τ :
-
parameter defined by Eq. (6)
- ϕ :
-
nanoparticles volume fraction
- ϕ w :
-
nanoparticles volume fraction at the vertical plate
- ϕ ∞ :
-
ambient nanoparticles volume fraction attained as y → ∞
- ψ :
-
stream function
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Hady, F.M., Ibrahim, F.S., Abdel-Gaied, S.M. et al. Boundary-layer non-Newtonian flow over vertical plate in porous medium saturated with nanofluid. Appl. Math. Mech.-Engl. Ed. 32, 1577–1586 (2011). https://doi.org/10.1007/s10483-011-1524-7
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DOI: https://doi.org/10.1007/s10483-011-1524-7