Effect of heat generation or absorption on thermophoretic free convection boundary layer from a vertical flat plate embedded in a porous medium ☆ Ali J. Chamkha a , Ali F. Al-Mudhaf a , Ioan Pop b, ⁎ a Manufacturing Engineering Department, PAAET, Shuweikh, Kuwait b Faculty of Mathematics, University of Cluj, R-3400 Cluj, CP 253, Romania Available online 17 May 2006 Abstract This paper is focused on the study of coupled heat and mass transfer by boundary-layer free convection over a vertical flat plate embedded in a fluid-saturated porous medium in the presence of thermophoretic particle deposition and heat generation or absorption effects. The governing partial differential equations are transformed into ordinary differential equations by using special transformations. The resulting similarity equations are solved numerically by an efficient implicit tri-diagonal finite-difference method. Comparisons with previously published work are performed and the results are found to be in excellent agreement. Many results are obtained and a representative set is displayed graphically to illustrate the influence of the heat generation or absorption coefficient, buoyancy ratio and the Lewis number on the temperature and concentration profiles and the wall thermophoretic deposition velocity. © 2006 Elsevier Ltd. All rights reserved. Keywords: Coupled heat and mass transfer; Vertical flat plate; Porous medium; Thermophoresis 1. Introduction Thermophoresis is a phenomenon which causes small particles to be driven away from a hot surface and towards a cold one. Small particles, such as dust, when suspended in a gas with a temperature gradient, experience a force in the direction opposite to the temperature gradient. This phenomenon has many practical applications in removing small particles from gas streams, in determining exhaust gas particle trajectories from combustion devices, and in studying the particulate material deposition on turbine blades. It has also been shown that thermophoresis is the dominant mass transfer mechanism in the modified chemical vapor deposition process used in the fabrication of optical fiber perform and is also important in view of its relevance to postulated accidents by radioactive particle deposition in nuclear reactors. In many industries the composition of processing gases may contain any of an unlimited range of particle, liquid, or gaseous contaminants and may be influenced by uncontrolled factors of temperature and humidity. When International Communications in Heat and Mass Transfer 33 (2006) 1096 – 1102 www.elsevier.com/locate/ichmt ☆ Communicated by W.J. Minkowycz. ⁎ Corresponding author. E-mail address: pop.ioan@yahoo.co.uk (I. Pop). 0735-1933/$ - see front matter © 2006 Elsevier Ltd. All rights reserved. doi:10.1016/j.icheatmasstransfer.2006.04.009