In the present work, the unsteady and steady state heat transfer by natural convection in heat sinks, horizontally oriented, with flat and rectangular fins was studied. For that, the free and open source CFD software OpenFOAM (Open Field Operation and Manipulation) was used to solve the three-dimensional equations of continuity, momentum and energy. The Finite Volume Method for the discretization of the governing equations and the PIMPLE solution algorithm for the pressure-velocity coupling were used. The temperature, velocity and vorticity fields were numerically obtained. Experiments were also carried out to validate the computational studies. Two 6063-T5 aluminum heat sinks were studied. In addition, analyses were realized in the relation between the power provided and the temperature that has been achieved by the heat sink. Through this relation, the heat sinks can be classified and identified according to their capacity to dissipate heat. The values of the average convection heat transfer coefficient and the Nusselt number, numerically obtained, were compared with the experimental values. These results obtained were in accordance with the empirical correlation found in literature, with average differences lower than 10%.
Papers presented to the 12th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Costa de Sol, Spain on 11-13 July 2016.