International Journal of Computer Applications (0975 – 8887) Volume 119 – No.21, June 2015 5 Effect of Chemical Reaction on Mass Transfer due to a Permeable Rotating Heated Disk B.R. Sharma Department of Mathematics Dibrugarh University Hemanta Konwar Research Scholar Department of Mathematics Dibrugarh University ABSTRACT An unsteady three dimensional flow in an incompressible viscous, chemically reacting fluid mixture due to a permeable rotating heated disk is studied by taking into account the effects of magnetic field, ohmic heating, viscous dissipation, chemical reaction and suction or injection. The system of non- linear partial differential equations governing the flow, heat and mass transfer is reduced to a system of nonlinear ordinary differential equations by using similarity transformations. The resulting system of ordinary coupled nonlinear differential equations is solved numerically by bvp4c and solutions are presented graphically. All numerical calculations are done with respect to air at 20 0 C (Pr = 0.71) in presence of Hydrogen (Sc = 0.22). Numerical values of the local skin frictions and the rate of heat and mass transfers are shown in tables. Keywords Unsteady flow, Rotating Disk, Magnetic effect, Viscous dissipation, Ohmic heating, Chemical reaction. 1. INTRODUCTION Flow due to a rotating disk is one of the classical problems of fluid mechanics and has several applications in engineering and industries such as rotating machinery like computer storage devices, gas turbine rotors, centrifugal pumps, rotational viscometers and some aerodynamic related problems. The first solution to the problem of rotating disk flow was obtained by von Karman (1921). The solution was further improved by Cochran (1934). Wagner (1948) discussed heat transfer from a rotating disk to ambient air. Millsaps and Pohlhausen (1952) discussed heat transfer by laminar flow from a rotating plate. Benton (1966) improved Cochran’s solutions and solved the unsteady problem. Finding the importance of suction or injection Kuiken(1971) studied the effect of normal blowing on the flow near a rotating disk of infinite extent. Georges (1989) numerically studied convective heat transfer over a rotating rough disk with uniform wall temperature. Cheng and Lin (1994) discussed unsteady and steady mass transfer by laminar forced flow against a rotating disk. Hassan and Attia (1997) investigated the steady magneto hydro dynamics boundary layer flow due to an infinite disk rotating with uniform angular velocity in presence of the Hall current. Alam and Sattar (1998) considered the unsteady MHD free convection and mass transfer flow in a rotating system with thermal diffusion. Attia (1998) studied the unsteady MHD flow near a rotating porous disk with uniform suction or injection. Takhar et al. (2002) carried out study on the unsteady MHD flow and heat transfer on a rotating disk in an ambient fluid. Maleque and Sattar (2003) further studied the transient convective flow due to a rotating disc with magnetic field and heat absorption effects. Attia (2006) continued study on the unsteady flow and heat transfer of viscous incompressible fluid with temperature dependent viscosity due to a rotating disc in a porous medium. Osalusi et al. (2007) studied the effects of Ohmic heating and viscous dissipation on unsteady MHD and slip flow over a porous rotating disk. Sharma and Singh (2010) discussed thermal diffusion in a binary fluid mixture flow due to a rotating disk of uniform high suction in presence of a weak axial magnetic field. Sibanda and Makinde (2010) investigated steady MHD flow and heat transfer past a rotating disk in a porous medium with ohmic heating and viscous dissipation. Maleque (2010) studied Dufour and Soret effects on unsteady MHD convective heat and mass transfer flow due to a rotating disk. Mustafa (2012) considered MHD fluid flow and heat transfer due to a stretching rotating disk. Khidir (2013) considered the effect of viscous dissipation, ohmic heating and radiation on MHD flow past a rotating disk embedded in a porous medium with variable properties. It was found that none of the above mentioned authors took into account the effects of chemical reaction and its order. Therefore present authors have the curiosity to investigate the effect of chemical reaction and its order on unsteady flow due to a permeable rotating heated disk. Chemical reaction have several industrial applications such as food processing, cooling of nuclear reactors, underground energy transport, magnetized plasma flow, polymer production, manufacturing of ceramic and enhanced oil recovery. Mass transfer proceeds as long as there is a difference in concentrations of some chemical species in the mixture. Chemical reaction processes can be classified into two broad categories namely homogeneous and heterogeneous. A chemical reaction is said to be homogeneous reaction if it occurs uniformly throughout a given phase and heterogeneous if it takes place in a restricted area or within the boundary of a phase. A chemical reaction is said to be of order n if the rate of reaction is proportional to the nth power of concentration. The order of the chemical reaction depends on several factors. One of the simplest chemical reactions is the first order reaction in which the rate of reaction is directly proportional to the species concentration. Second and third order chemical reactions are usually destructive in nature. The aim of this paper is to investigate the effect of chemical reaction and its order on mass transfer due to a permeable rotating heated disk in presence of the magnetic field, ohmic heating, viscous dissipation. The system of non-linear partial differential equations governing the unsteady flow, heat and mass transfer is first converted in to a system of ordinary differential equations by using suitable transformations and then solved by using bvp4c.