Buoyancy-induced convection in Al2O3/water nanofluids from an enclosed heater

Laminar natural convection of nanofluids inside square cavities partially heated at one side and cooled at the opposite side is studied numerically. A computational code based on the SIMPLE-C algorithm is used for the solution of the system of the mass, momentum and energy transfer governing equations in which the thermophysical properties are the effective properties of the nanofluid. In particular, the effective thermal conductivity and dynamic viscosity are calculated by means of a couple of empirical equations based on a wide variety of experimental data-sets available in the literature, whereas the other relevant effective properties have been evaluated by the conventional mixing theory. Simulations are performed in the hypothesis of temperature-dependent effective properties, using the diameter of the suspended nanoparticles and their volume fraction, the size of the cavity, the length of the heater and its position, as well as the temperatures of the heated and cooled boundary surfaces, as independent variables. It is found that the heat transfer performance has a peak at optimal particle loadings and heater positions. Based on the results obtained, a set of correlations is developed.