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Numerical Heat Transfer, Part B: Fundamentals
An International Journal of Computation and Methodology
Volume 71, 2017 - Issue 4
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Original Articles

Spectral Fourier–Galerkin benchmark solution for natural convection in an inclined saturated porous medium

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Pages 372-395 | Received 16 Jul 2016, Accepted 04 Nov 2016, Published online: 31 Mar 2017
 

ABSTRACT

This paper presents some novel problems associated with the steady natural convection flow in an inclined square cavity filled with a saturated porous medium. The proposed method is a high-accurate spectral method based on the Fourier–Galerkin technique. The numerical results have demonstrated the advantage for the following reasons. (a) The high-accurate method deals with inclined geometries successfully. (b) The streamlines, isotherms, and the average Nusselt numbers are affected significantly by the inclination of the cavity for high values of Rayleigh number. (c) In contrast with the finite element method a highly accurate and efficient solution with less computational effort is obtained.

Nomenclature

A=

stream function coefficients

B=

temperature coefficients

g=

acceleration due to gravity

k=

permeability

L=

cavity square side

Nc=

total number of Fourier coefficients

Ne=

total number of mesh elements

Nm=

stream function truncation order in X

Nn=

stream function truncation order in Y

Nr=

temperature truncation order in X

Ns=

temperature truncation order in Y

Nu=

local Nusselt number

P=

pressure

Ra=

local Rayleigh number

RF=

flow equation residual

RH=

heat transfer equation residual

t=

time

T=

temperature

ϕ=

the inclination angle

u=

velocity component in the x direction

U=

dimensionless velocity component in the x direction (= uL/α)

v=

velocity component in the Y direction

V=

dimensionless velocity component in the Y direction (= vL/α)

Umax=

dimensionless maximum horizontal at the mid-plane X = 0.5

Vmax=

dimensionless maximum vertical velocity at the mid-plane Y = 0.5

X=

dimensionless horizontal coordinate (= x/L)

x,y=

vertical and horizontal coordinate

Y=

dimensionless vertical coordinate (= y/L)

α=

effective thermal diffusivity

β=

coefficient of thermal expansion of fluid

δ=

Kronecker delta function

ΔT=

temperature difference

ε=

ratio of composite material to convective fluid heat capacities

ρ=

fluid density

μ=

fluid viscosity

υ=

temperature change of variable

θ=

dimensionless temperature

ϖ=

dimensionless stream function

φ=

stream function

χ=

trial function for heat transfer equation

ϑ=

trial function for the flow equation

γ=

matrix coefficient

ξ=

matrix coefficient

λ=

matrix coefficient

τ=

matrix coefficient

Γ=

matrix coefficient

Λ=

matrix coefficient

ϒ=

matrix coefficient

Φ=

vector coefficient

Subscripts=
c=

cold fluid

h=

hot fluid

Nomenclature

A=

stream function coefficients

B=

temperature coefficients

g=

acceleration due to gravity

k=

permeability

L=

cavity square side

Nc=

total number of Fourier coefficients

Ne=

total number of mesh elements

Nm=

stream function truncation order in X

Nn=

stream function truncation order in Y

Nr=

temperature truncation order in X

Ns=

temperature truncation order in Y

Nu=

local Nusselt number

P=

pressure

Ra=

local Rayleigh number

RF=

flow equation residual

RH=

heat transfer equation residual

t=

time

T=

temperature

ϕ=

the inclination angle

u=

velocity component in the x direction

U=

dimensionless velocity component in the x direction (= uL/α)

v=

velocity component in the Y direction

V=

dimensionless velocity component in the Y direction (= vL/α)

Umax=

dimensionless maximum horizontal at the mid-plane X = 0.5

Vmax=

dimensionless maximum vertical velocity at the mid-plane Y = 0.5

X=

dimensionless horizontal coordinate (= x/L)

x,y=

vertical and horizontal coordinate

Y=

dimensionless vertical coordinate (= y/L)

α=

effective thermal diffusivity

β=

coefficient of thermal expansion of fluid

δ=

Kronecker delta function

ΔT=

temperature difference

ε=

ratio of composite material to convective fluid heat capacities

ρ=

fluid density

μ=

fluid viscosity

υ=

temperature change of variable

θ=

dimensionless temperature

ϖ=

dimensionless stream function

φ=

stream function

χ=

trial function for heat transfer equation

ϑ=

trial function for the flow equation

γ=

matrix coefficient

ξ=

matrix coefficient

λ=

matrix coefficient

τ=

matrix coefficient

Γ=

matrix coefficient

Λ=

matrix coefficient

ϒ=

matrix coefficient

Φ=

vector coefficient

Subscripts=
c=

cold fluid

h=

hot fluid

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