Analysis of natural convection in heat sink using OpenFOAM and experimental tests

A transient three-dimensional natural convection problem in heat sinks with rectangular fins positioned horizontally was studied using the software OpenFOAM (Open Field Operation and Manipulation). OpenFOAM is based on the Finite Volume Method for the discretization of the governing equations and was used to solve the three-dimensional equations of continuity, momentum and energy. These computational simulations were done with the PIMPLE solution algorithm for decoupling the equations. The NusseltCalc tool was used in the post-processing to obtain Nusselt number. The results of Nusselt number, temperature, velocity and vorticity fields were obtained. The temperature results were also obtained by numerical probes and compared with experimental and analytical results; presenting differences lower than 0.7%. The results of the average Nusselt number, Nu, and the average heat transfer coefficient by convection, <h, numerically obtained with OpenFOAM were compared with the experimental and with those obtained from empirical correlation. All these results obtained with OpenFOAM presented good accordance with experiments and literature with differences lower than 10%. Uncertainty analyses were also carried out in order to prove the quality of the results and they presented differences lower than 5%. In addition, a Nusselt number correlation is proposed for Rayleight number in the range of 4.6x10(4)<Ra<5.8x10(5).