UNSTEADY MHD BUOYANCY INDUCED FLOW PAST AN ACCELERATED VERTICAL PLATE WITH CHEMICAL REACTION Sujan Sinha * Department of Mathematics, Assam downtown University, Guwahati, Assam-781026 Email: mathssujangu@gmail.com Abstract An exact solution to the problem of a viscous incompressible electrically conducting fluid past an accelerated vertical plate with uniform mass diffusion is obtained. A uniform magnetic field is assumed to be applied normal to the plate directed to the fluid region. The equations governing the flow are solved analytically by adopting Laplace transform technique in closed form. The expressions for the profiles of velocity, temperature, concentration, skin-friction, Nusselt number and Sherwood number are obtained. The profiles of velocity, concentration, skin-friction and Sherwood number are demonstrated graphically for various values of the parameters involved in the problem and physical interpretation of the results are demonstrated. Keywords: MHD, Thermal radiation, Mass transfer, Chemical reaction, Sherwood number 1. Introduction Many natural phenomena and technological problems are susceptible to MHD analysis. Geophysics encounters MHD characteristics in the interactions of conducting fluids and magnetic fields. Engineers employ MHD principle, in the design of heat exchangers pumps and flow meters, in space vehicle propulsion, thermal protection, braking, control and re-entry, in creating novel power generating systems etc. From technological point of view, MHD convection flow problems are also very significant in the fields of stellar and planetary magnetospheres, aeronautics, chemical engineering and electronics. Model studies of the above phenomena of MHD convection have been made by many. Many researchers have studied the phenomena of MHD free convection and mass transfer flow of whom the names of Acharya et al [2000], Raptis and Kafousias [1982] , and Singh and Singh [2000] respectively. The study of effect of chemical reaction on heat and mass transfer in a flow is of great practical importance to the Engineers and Scientists because of its almost universal occurrence in many branches of Science and technology. In processes such as drying, distribution of temperature and moisture over agricultural fields, energy transfer in a wet cooling tower and flow in a cooler heat and mass transfer occur simultaneously. Possible applications of this type of flow can be found in many industries. Chambre and Young [1958] have presented a first order chemical reaction in the neighbourhood of a horizontal plate. Many investigators have studied the effect of chemical reaction in different types of flows regarding convective heat and mass transfer. Some of them are Alam et al. [2006], Ahmed and Kalita [2009] etc. Still now there were not any kind of attempt made by many researchers to study the effect of chemical reaction on a three dimensional MHD independent flow of a viscous incompressible electrically conducting fluid bounded by an infinite vertical isothermal plate. Therefore such kinds of investigations are tried in the present paper. The main objective of the present paper is to study the effect of chemical reaction on a three dimensional MHD independent flow of a viscous incompressible electrically conducting fluid past an infinite vertical isothermal plate. In the present study, the imposition of transverse magnetic field can not be neglected. So with chemical reaction, it is also proposed to study the effects of magnetic field to strengthen in the present study. This work is a generalization to the work done by Ahmed and Sinha [2014] to consider the effects chemical reaction. In the present paper, the solutions and the results obtained without chemical reaction are found to be consistent with the work done by Ahmed and Sinha [2014]. 2. Mathematical Formulation We now consider a three dimensional MHD time dependent flow of a viscous incompressible fluid induced by uniformly accelerated motion with uniform mass diffusion in a rotating fluid under the influence of an applied transverse magnetic field. To idealize the flow model, we have taken the following assumptions: ISSN (Print) : 2278–9510 ISSN (Online) : 0975-5462 Sujan Sinha / International Journal of Engineering Science and Technology (IJEST) DOI: 10.21817/ijest/2018/v10i2S/181002S034 Vol. 10 No.02S Feb 2018 185