Coupled heat and mass transfer by natural convection adjacent to a permeable horizontal cylinder in a saturated porous medium

The heat and mass transfer characteristics of free convection about a perme able horizontal cylinder embedded in porous media under the coupled effects of thermal and mass diffusion are numerically analyzed. The surface of the horizontal cylinder is maintained at a uniform wall temperature and unifor m wall concentration. The transformed governing equations are obtained and solved by Keller box method. Numerical results for the dimensionless temper ature profiles, the dimensionless concentration profiles, the Nusselt numbe r and the Sherwood number are presented. Increasing the buoyancy ratio N an d the transpiration parameter f(w) increases the Nusselt number and the She rwood number. For thermally assisting flow, when Lewis number Le increases, the Nusselt (Sherwood) number decreases (increases). Whereas, for thermall y opposing flow, both the Nusselt number and the Sherwood number increase w ith increasing the Lewis number. (C) 1999 Elsevier Science Ltd.