Abstract
The present work deals with entropy generation rate due to flow and heat transfer by unsteady natural convection coupled with thermal radiation within a vertical channel open at both ends and filled with a semi-transparent porous medium. The radiative transfer equation is solved by the finite volume method. The governing equations for this problem and the relevant boundary conditions are non-linear differential equations depending on different dimensionless numbers. Various results are obtained for the average dimensionless conductive, convective, radiative and total Nusselt numbers for different combinations of the Planck number
N
, optical thickness
τ
, walls’ emissivity
, single scattering albedo
ω
and temperature ratio
R
. The present work mainly investigates the rate of local as well as total entropy generation enhancement due to radiation. Profiles of spatial variations of local entropy generation rate and time variations of the total entropy generation rate are presented for different values of
and 0.1 ≤
R
≤ 0.9.