The present work deals with the natural convection in a square cavity filled
with the water-based Au nanofluid. The cavity is heated on the vertical and
cooled from the adjacent wall, while the other two horizontal walls are
adiabatic. The governing differential equations have been solved by the
standard finite volume method and the hydrodynamic and thermal fields were
coupled together using the Boussinesq approximation. The main objective of
this study is to investigate the influence of the nanoparticles? volume
fraction on the heat transfer characteristics of Au nanofluids at the given
base fluid?s (i.e. water) Rayleigh number. Accurate results are presented
over a wide range of the base fluid Rayleigh number and the volume fraction
of Au nanoparticles. It is shown that adding nanoparticles in a base fluid
delays the onset of convection. Contrary to what is argued by many authors,
we show by numerical simulations that the use of nanofluids can reduce the
heat transfer rate instead of increasing it.