1 - Acta Technica Corviniensis

1.A.G. VIJAYA KUMAR, 2. S.V.K. VARMA, 3. Y. RAJASHEKARA GOUD, 4. K. RAGHUNATHTHERMAL DIFFUSION AND RADIATION EFFECTS ON UNSTEADYMHD FLOW PAST A LINEARLY ACCELERATED VERTICAL PLATE WITHVARIABLE TEMPERATURE AND MASS DIFFUSION1. DEPARTMENT OF MATHEMATICS, MVJ COLLEGE OF ENGINEERING, BANGLORE, KARNATAKA, INDIA2.DEPARTMENT OF MATHEMATICS, S.V.UNIVERSITY, TIRUPATI, A.P, INDIA3. DEPARTMENT OF HUMANITIES AND SCIENCES, G. PULLAREDDY ENGINEERING COLLEGE, KURNOOL, A.P, INDIA4.DEPARTMENT OF MATHEMATICS, BHEEMA INSTITUTE OF TECHNOLOGY AND SCINECE, ADONI, KURNOOL, A.P. INDIAABSTRACT: The objective of the present study is to investigate thermal diffusion and radiation effects on unsteady MHD flowpast a linearly accelerated vertical plate with variable temperature and mass diffusion under the influence of appliedtransverse magnetic field. The fluid considered here is a gray, absorbing/ emitting radiation but a non‐scattering medium.At time t>0, the plate is linearly accelerated with a velocity u = u 0 t in its own plane. And at the same time, platetemperature and concentration levels near the plate raised linearly with time t. The dimensionless governing equationsinvolved in the present analysis are solved using the Laplace transform technique. The velocity, temperature,concentration, Skin‐friction, the rate or heat transfer and the rate of mass transfer are studied through graphs and tables interms of different physical parameters like magnetic field parameter (M), radiation parameter (R), Schmidt parameter (Sc),soret number (So), Prandtl number (Pr), thermal Grashof number (Gr), mass Grashof number (Gm) and time (t).KEYWORDS: magnetic field, radiation, thermal diffusion, vertical plate, porous mediumINTRODUCTIONThe study of magneto hydro‐dynamics with mass andheat transfer in the presence of radiation anddiffusion has attracted the attention of a largenumber of scholars due to diverse applications. Inastrophysics and geophysics, it is applied to study thestellar and solar structures, radio propagationthrough the ionosphere, etc. In engineering we find itsapplications like in MHD pumps, MHD bearings, etc.The phenomenon of mass transfer is also verycommon in theory of stellar structure and observableeffects are detectable on the solar surface. In freeconvection flow the study of effects of magnetic fieldplay a major rule in liquid metals, electrolytes andionized gases. In power engineering, the thermalphysics of hydro magnetic problems with masstransfer have enormous applications. Radiative flowsare encountered in many industrial and environmentprocesses, e.g. heating and cooling chambers, fossilfuel combustion energy processes, evaporation fromlarge open water reservoirs, astrophysical flows, solarpower technology and space vehicle re‐entry.MHD effects on impulsively started vertical infiniteplate with variable temperature in the presence oftransverse magnetic field were studied bySoundalgekar et al. [12]. The effects of transverselyapplied magnetic field, on the flow of an electricallyconducting fluid past an impulsively started infiniteisothermal vertical plate were also studied bySoundalgekar et al. [11]. The dimensionless governingequations were solved using Laplace transformtechnique. Kumari and nath [8] studied thedevelopment of the asymmetric flow of a viscouselectrically conducting fluid in the forward stagnationpoint region of a two‐dimensional body and over astretching surface was set into impulsive motion fromthe rest. The governing equations were solved usingfinite difference scheme. The radiative free convectionflow of an optically thin gray‐gas past semi‐infinitevertical plate studied by Soundalgekar and Takhar[13]. Hossain and Takhar have considered radiationeffects on mixed convection along an isothermalvertical plate [5]. In all above studies the stationaryvertical plate considered. Raptis and Perdikis [10]studied the effects of thermal‐radiation and freeconvection flow past a moving vertical plate. Thegoverning equations were solved analytically. Das et al[4] have considered radiation effects on flow past animpulsively started infinite isothermal vertical plate.The governing equations were solved by the Laplacetransform technique. Muthucumaraswamy andJanakiraman [9] have studied MHD and radiationeffects on moving isothermal vertical plate withvariable mass diffusion.Alam and Sattar [3] have analyzed the thermaldiffusioneffect on MHD free convection and masstransfer flow. Jha and Singh [6] have studied theimportance of the effects of thermal‐diffusion (massdiffusion due to temperature gradient). Alam et al [1]studied the thermal‐diffusion effect on unsteady MHDfree convection and mass transfer flow past animpulsively started vertical porous plate. Recently,Alam et al [2] studied combined free convection andmass transfer flow past a vertical plate with heat© copyright FACULTY of ENGINEERING ‐ HUNEDOARA, ROMANIA 67