The present paper is concerned to analyze the influence of the unsteady free convection flow of a viscous incompressible fluid through a porous medium with high porosity bounded by a vertical infinite moving plate in the presence of thermal radiation, heat generation, and chemical reaction. The fluid is considered to be gray, absorbing, and emitting but nonscattering medium, and Rosseland approximation is considered to describe the radiative heat flux in the energy equation. The dimensionless governing equations for this investigation are solved analytically using perturbation technique. The effects of various governing parameters on the velocity, temperature, concentration, skin-friction coefficient, Nusselt number and Sherwood number are shown in figures and tables and analyzed in detail. 1. Introduction Transport of momentum and energy in fluid-saturated porous media with low porosities are commonly described by Darcy’s model for conservation of momentum and by an energy equation based on the velocity field found from this model by Kaviany [1]. In contrast to rocks, soil, sand, and other media that do fall in this category, certain porous materials, such as foam metals and fibrous media, usually have high porosity. Vajravelu [2] examined the steady flow of heat transfer in a porous medium with high porosity. Raptis [3] studied mathematically the case of time varying two-dimensional natural convection heat transfer of an incompressible electrically conducting viscous fluid through a high porous medium bounded by an infinite vertical porous plate. Hong et al. [4], Chen and Lin [5], and Jaiswal and Soundalgekar [6] studied the natural convection in a porous medium with high porosity. Hiremath and Patil [7] studied the effect of free convection currents on the oscillatory flow of the polar fluid through a porous medium, which is bounded by the vertical plane surface with constant temperature. Many processes in engineering areas occur in high temperature and consequently the radiation plays a significant role. Chandrasekhara and Nagaraju [8] examined the composite heat transfer in a variable porosity medium bounded by an infinite vertical flat plate in the presence of radiation. Yih [9] studied the radiation effects on natural convection over a cylinder embedded in porous media. Mohammadein and El-Amin [10] considered the thermal radiation effects on power law fluids over a horizontal plate embedded in a porous medium. Raptis [11] studied the heat transfer in a porous medium with high porosity in the presence of radiation. Raptis and Perdikis [12] studied
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