Water-Alumina natural convection heat transfer in an inclined L shape cavity ABSTRACT A numerical investigation of water-alumina natural convection laminar flow in an inclined L shape cavity is performed. Two wall of the cavity are hot with the temperature of Th, two walls are cold with the temperature of Tc , and two other walls are thermally adiabatic. The two dimensional continuity, momentums and energy equations are solved numerically with a finite volume approach using the well known SIMPLE algorithm. The influence of pertinent parameters such as Rayleigh number, Ra, solid volume fraction, , inclination angle, , and cavity aspect ratio, A, on the fluid flow, fluid temperature and cavity heat transfer characteristics is studied. The results indicate that nanofluid with higher nanoparticles has better performance. The results also show that the inclination angle has a significant effect on the heat transfer performance at high Rayleigh numbers. Keywords: Natural convection, nanofluid, L shape cavity, Rayleigh number.