Modeling of Rayleigh-Benard natural convection heat transfer in nanofluids

Heat transfer in Rayleigh-Benard convection is investigated for three types of nanofluid. Instead of using the expressions commonly found in the literature for specific heat capacity and thermal expansion coefficient, we used two relations that are in agreement with the laws of thermodynamics. The influence of nanoparticles on conductive and convective heat transfer is studied. It is shown that adding nanoparticles in a fluid delays the onset of convection. Contrary to what is argued by many authors, we prove by direct numerical simulations that the use of nanofluids can reduce heat transfer instead of increasing it. (C) 2010 Academie des sciences. Published by Elsevier Masson SAS. All rights reserved.