© 2019 JETIR February 2019, Volume 6, Issue 2 www.jetir.org (ISSN-2349-5162) JETIR1902066 Journal of Emerging Technologies and Innovative Research (JETIR) www.jetir.org 485 Dufour and Radiation absorption effects on unsteady MHD free convection Casson fluid flow past an exponentially infinite vertical plate through porous medium. S. Rama Mohan 1* , Prof. G. Viswanatha Reddy 2 , Prof.S.V.K.Varma 2 1,2, Department of Mathematics, S.V.University, Tirupathi-517502,A.P,India. Abstract: The aim of the present paper is to study the effects of Dufour and Radiation absorption on an unsteady MHD free convection Casson fluid flow past an exponentially an infinite vertical plate through porous medium in the presence of thermal radiation and heat source or sink. Chemical reaction is assumed in the first order. The set of non-dimensional partial differential equations are solved analytically by using the Laplace transform technique. The influence of various non-dimensional parameters on the velocity, the temperature, the concentration, the skin friction, the local Nusselt and the Sherwood numbers are discussed and derived through graphs and tables. The velocity profile decreases with increases the values of Magnetic parameter, Radiation absorption, chemical reaction and thermal radiation. The temperature profile increases with an increase the values of thermal radiation and Dufour number. Keywords: Casson fluid, Dufour, Radiation absorption, MHD, thermal radiation and chemical reaction. Introduction The study of non-Newtonian fluid through porous medium has number of applications in science and Engineering. The number of investigators has investigated in non-Newtonian fluid like Casson fluid which exhibits the yield stress. In the human body the blood also can be treated as Casson fluid. Casson fluid model is widely used in food stuffs and biological materials, especially blood. It describes the steady shear stress and shear rate behavior of blood. The number of investigators has investigated their pioneer work done by Casson [1] analyzed a flow equation for pigment oil suspensions of the printing ink type. The application of the minimal energy hypothesis to a Casson fluid was studied by Mcgregor [2]. A mathematical study of peristaltic transport of a Casson fluid was found by Mermone et al. [3]. Raptis and Perdikis [4] examined unsteady flow through a highly porous medium in the presence of radiation. Boyd et al. [5] discussed analysis of the Casson and Carreau-Yasuda non-Newtonian blood models in steady and oscillatory flows using the lattice boltzmann method. Unsteady boundary layer flow of a Casson fluid due to an impulsively started moving flat plate was discussed by Mustafa et al. [6]. Raptis [7] analyzed free convective oscillatory flow and mass transfer past a porous plate in the presence of radiation for an optically thin fluid. Soret and Dufour effects on the magneto hydrodynamic (MHD) flow of the Casson fluid over a stretched