Horizontal boundary-layer natural convection in a porous medium saturated with a gas

1991 ◽  
Vol 6 (2) ◽  
Author(s):  
Ioan Pop ◽  
RamaSubba Reddy Gorla
Keyword(s):  
Boundary Layer ◽  
Porous Medium ◽  
Natural Convection ◽  
Horizontal Boundary

Unsteady Natural Convection Heat Transfer Past a Vertical Flat Plate Embedded in a Porous Medium Saturated With Fractional Oldroyd-B Fluid

2016 ◽  
Vol 139 (1) ◽  
Author(s):  
Jinhu Zhao ◽  
Liancun Zheng ◽  
Xinxin Zhang ◽  
Fawang Liu ◽  
Xuehui Chen
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Porous Medium ◽  
Natural Convection ◽  
Prandtl Number ◽  
Fractional Derivative ◽  
Convection Heat Transfer ◽  
Natural Convection Heat Transfer ◽  
Convection Heat ◽  
Elastic Effect

This paper investigates natural convection heat transfer of generalized Oldroyd-B fluid in a porous medium with modified fractional Darcy's law. Nonlinear coupled boundary layer governing equations are formulated with time–space fractional derivatives in the momentum equation. Numerical solutions are obtained by the newly developed finite difference method combined with L1-algorithm. The effects of involved parameters on velocity and temperature fields are presented graphically and analyzed in detail. Results indicate that, different from the classical result that Prandtl number only affects the heat transfer, it has remarkable influence on both the velocity and temperature boundary layers, the average Nusselt number rises dramatically in low Prandtl number, but increases slowly with the augment of Prandtl number. The maximum value of velocity profile and the thickness of momentum boundary layer increases with the augment of porosity and Darcy number. Moreover, the relaxation fractional derivative parameter accelerates the convection flow and weakens the elastic effect significantly, while the retardation fractional derivative parameter slows down the motion and strengthens the elastic effect.

An Integral Treatment for Dissipative Boundary Layer Flow along a Radiating Vertical Surface by Natural Convection in a Porous Medium

2017 ◽  
Vol 11 ◽  
pp. 191-207 ◽  
Author(s):  
Shoeb R. Sayyed ◽  
B.B. Singh ◽  
Nasreen Bano
Keyword(s):  
Boundary Layer ◽  
Porous Medium ◽  
Natural Convection ◽  
Radiation Effects ◽  
Lewis Number ◽  
Vertical Surface ◽  
Integral Treatment ◽  
Layer Flow ◽  
Dissipative Boundary ◽  
Local Sherwood Number

In the present study, an integral method of Von Karman type has been used to analyse the phenomenon of natural convection heat and mass transfer near a vertical surface embedded in a fluidsaturated porous medium considering the viscous dissipation and radiation effects. The buoyancy effect is due to the variation of temperature and concentration across the boundary layer. The effects of the governing parameters e.g. buoyancy ratio (N), Lewis number (Le), Eckert number (Ec) and radiation parameter (R) on local Nusselt number, local Sherwood number, velocity profile, temperature profile and concentration profile have been investigated. The results obtained in the present analysis have been compared with the published results available in the literature and they have been found in precise agreement.

Natural Convection Near a Cold Plate Facing Upward in a Porous Medium

1985 ◽  
Vol 107 (4) ◽  
pp. 819-825 ◽  
Author(s):  
S. Kimura ◽  
A. Bejan ◽  
I. Pop
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Porous Medium ◽  
Natural Convection ◽  
Numerical Solutions ◽  
Cold Plate ◽  
Flow Features ◽  
Sharp Edges ◽  
Layer Flow ◽  
Heat And Fluid Flow

It is shown that the phenomenon of natural convection driven in a porous medium by a cold plate facing upward or by a warm plate facing downward consists of a finite-length boundary layer flow chopped off by the sharp edges of the plate. The heat and fluid flow features of the boundary layer are determined analytically employing scale analysis and integral analysis. The overall heat transfer rate between porous medium and plate is found to vary as Nu/Ra1/3 = 0(1), where Ra is the Darcy-modified Rayleigh number based on plate half-length. The boundary layer features of the flow and the heat transfer effected by it are confirmed in the Ra range 100–700 by numerical solutions of the complete partial differential equations.

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