Experimental measurements and numerical simulations of natural convection in a cubical cavity heated from below and cooled from above are reported at turbulent Rayleigh numbers using water as a convective fluid (Pr = 6.0). Direct numerical simulations were carried out considering the Boussinesq approximation with a second-order finite volume code (10(7) <= Ra <= 10(8)). The particle image velocimetry technique was used to measure the velocity field at Ra = 10(7), Ra = 7 x 10(7) and Ra = 10(8) and there was general agreement between the predicted time averaged local velocities and those experimentally measured if the heat conduction through the sidewalls was considered in the simulations. (C) 2007 Elsevier Ltd. All rights reserved.