INTRODUCTION:

Many processes in engineering areas occur at high temperature making the knowledge of thermal radiation heat transfer very important .Plasma physics ,gas turbines and the various propulsion devices for aircraft ,missiles ,satellites and space vehicles, flow through a porous medium in the presence of radiation and glass production are some examplesof such engineering areas.

Seddeek et al.[1] studied the effects of radiation and thermal diffusivity in heat transfer over a stretching surface with variable heat flux .The free convection flow in the presence of radiation has been investigated by Hossain et al.[2,3] and Raptis et al. [4].The flow through porous mediumin the presenceof radiation has been studied by Raptis [5], Badruddin et al. [6] and Mukhopadhyay et al.[7].The magnetohydrodynamicflow in the presence of radiation has been analysed by Chamkha et al. [8] and Duwairi [9]. In all these studies the fluid was assumed to be optically thick.

England et al.[10] have studied the thermal radiation effects of an optically thin gray gas bounded by a stationary vertical plate .The hydromagnatic free convection flow with radiative heat transfer in a rotating and optically thin fluid has been studied by Bestman et al.[11].Raptis et al.[12] have studied the hydromagnatic free convection flow with radiative heat transfer for an optically thin fluid past a vertical plate when the induced magnatic field is taken into account .

Raptis et al. [13] have investigated the unsteady flow of an optically thin fluid in the presence of free convection and mass transfer .Manivannan et al.[14] have studied the free convection for one dimensional flow with radiative heat transfer for an optically thin fluid past a vertical oscillating plate in the presence of chemical radiation .Vijaylakshmi [15] studied the effects of the radiation on free convection flow past an impulsively started vertical plate in rotating fluid for optically thin fluid . Raptis et al.[16] studied the two dimensional free convective oscillatory flow and mass transfer past a porous plate in the presence of radiation for an optically thin fluid .

In this work, we study the three dimensional free convective oscillatory flow and mass transfer of viscous and optically thin gray fluid with transverse sinusoidal suction over a porous vertical plate in the presence of radiation. The fluid is a gray absorbing-emitting radiation but non scattering medium and dissipative heat has been neglected.

CONCLUSIONS:

An analysis is performed to study the free convective oscillatory flow and mass transfer past a porous plate in the presence of radiation for an optically thin fluid. The governing equations are solved numerically .The conclusions of the study are:

1. The velocity decreases with the increase of the radiation parameter.

2. The velocity increases with the increase of Grashof number .

3. The velocity decreases with the increase of the Schmidt number .

4. The temperature decreases with the increase of the radiation parameter.

NOMENCLATURE

REFERENCES

[1] Seddeek,M.A.,Abdelmeguid, M.S., Effects of Radiation and Thermal Diffusivity on Heat Transfer over a Stretching Surface with Variable Heat Flux, Physics Letter A,348(2006),3-6, pp. 172-179.

[2] Hossain, M.A, Alim ,M.A, Rees, D.A .S., The Effect of Radiation on Free convection from a Porous Vertical Plate, International Journal of Heat and Mass Transfer ,42(1999), 1,pp.181-191.

[3] Hossain , M.a, Khanafer ,K., Vafai, K., The Effect of Radiation on Free convection Flow of Fluid with Variable Viscosity from a Porous Vertical Plate , International Journal of Thermal Science ,40(2001),2 pp.115-124.

[4] Raptis, A., Toki, C. J., Thermal Radiation in the presence of Free convective Flow Past a Moving Vertical Porous Plate – An analytical Solution , Int.J.of Applied Mechanics and Engineering, 14(2009) 4,pp 1115-1126.

[5] Raptis, A., Radiation and Free convection Flow through a porous Medium, Int. Comm. Heat Mass Transfer, 25(1998), 2, pp. 289-295.

[6]badruddin, I. a., et al., Free convection and Radiation for a vertical Wall with Varying Temperature Embedded in a porous Medium, International journal of thermal Sciences, 45(2006) , 5,pp.487-493.

[7] Mukhopadhyay, S., Layek,G.C., Radiation Effect on Forced Convective Flow and Heat Transfer over a Porous Plate in a Porous Medium, Meccaanica,44(2009), 5, pp. 587-597.

[8] Chamkha, A.J.,et al., Thermal Radiation Effects on MHD Forced Covection Flow Adjacent to a Non- Isothermal Wedge in the Presence of a Heat source or Sink , Heat and Mass Transfer , 39(2003), 4, pp.305-312.

[9] Duwairi,H. M., Viscous and Joule Heating Effects on Forced Convection Flow from Radiate Isothermal Porous Surfaces, International Journal of Numerical Methods for Heat and Fluid Flow , 15(2005), 5-6, pp. 429-440.

[10] England,, W. g., Emerry, A.F.,Thermal Radiation Effects on the Laminar Free Convection Boundary Layer of an Absorving Gas, J.Heat Transfer , 91(1969), 1,pp. 37-44.

[11] Bestman, A.R., Adiepong, S.K., Unsteady Hydromagnatic Free Convection Flow with Radiative Heat Transfer in a Rotating Fluid , Astrophysics and space science, 143(1988), 1,pp.73-80.

[12] Raptis, a., Perdikis, C., Leontitsis,A., Effects of Radiation in an optically thin Gray Gas Flowing Past a vertical Infinite Plate in the Presence of a Magnatic Field , Heat and Mass Transfer ,39(2003), 8-9 pp.771-773.

[13] Raptis , A., Perdikis, C., Thermal Radiation of an optically thin Gray Gas, Int. J. of Applied Mechanics and Engineering, 8(2003), 1,pp. 131-134.

[14] Manivannan, K., Muthucumaraswamy, R., Thangaraj, V., Radiation and Chemical Reaction Effects on Isothermal Vertical Oscillating Plate with Variable Mass Diffusion, Thermal Science, 13(2009), 2, pp.155-162.

[15] Vijayalakshmi, A. R., Radiation Effects on Free-Convection Flow Past an Impulsively Started Vertical Plate in a Rotating Fluid ,Theoret. Appl.Mech., 37(2010) 2,pp.79-95.

[16] Raptis ,A., Free Convective Oscillatory Flow and Mass Transfer Past a Porous Plate in the Presence of Radiation for an Optically thin Fluid,Thermal Science,15(2011),3, pp.849-857.

Received on 12.12.2012 Accepted on 23.12.2012

Research J. Science and Tech 5(1): Jan.-Mar.2013 page 130-135