Hindawi Publishing Corporation Journal of Applied Mathematics Volume 2012, Article ID 939620, 10 pages doi:10.1155/2012/939620 Research Article Natural Convection in an Inclined Porous Cavity with Spatial Sidewall Temperature Variations M. S. Selamat, 1 R. Roslan, 2 and I. Hashim 3 1 Department of Mathematics & Statistics, Faculty of Computer & Mathematical Sciences, Universiti Teknologi MARA Pahang, 62400 Bandar Jengka, Malaysia 2 Faculty of Science, Technology and Human Development, Universiti Tun Hussein Onn Malaysia, Batu Pahat, Johor, 86400 Parit Raja, Malaysia 3 School of Mathematical Sciences and Solar Energy Research Institute, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, Selangor, 43600 Bangi, Malaysia Correspondence should be addressed to I. Hashim, ishak h@ukm.my Received 4 February 2012; Accepted 18 March 2012 Academic Editor: Hiroshi Kanayama Copyright q 2012 M. S. Selamat et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The natural convection in an inclined porous square cavity is investigated numerically. The left wall is assumed to have spatial sinusoidal temperature variations about a constant mean value, while the right wall is cooled. The horizontal walls are considered adiabatic. A finite difference method is used to solve numerically the nondimensional governing equations. The effects of the inclination angle of the cavity, the amplitude and wave numbers of the heated sidewall temperature variation on the natural convection in the cavity are studied. The maximum average Nusselt number occurs at different wave number. It also found that the inclination could influence the Nusselt number. 1. Introduction Convective heat transfer has attracted significant attention due to wide applications in engineering such as operation of solar collectors, cooling systems in electronics equipments, insulations of buildings and so forth. Many studies with application to the above research areas may be found in the book by Nield and Bejan 1. The problem of natural convection in an enclosure has been studied extensively by many researchers such as Weber 2, Bejan 3, Bradean et al. 4, Goyeau et al. 5, Guo and Bathe 6and Saeid and Pop 7. Saeid and Mohamad 8studied numerically the natural convection in a porous cavity with spatial sidewall temperature variation. They found that the average Nusselt number is dependent on the amplitude and the wave number of the spatial sinusoidal temperature. Saeid and Yaacob 9investigated the natural convection in