An assessment of computational fluid dynamic simulations and appropriate simplifications used for the development of LED luminaires

Driven by the thermal management demands of light emitting diodes (LEDs), the use of Computational Fluid Dynamics (CFD) by the lighting industry is growing. Establishing guidelines to ensure that these tools can be applied efficiently, i.e. sufficiently accurately without unnecessary complexity, would be very valuable to the industry. In this study a representative LED luminaire is assessed using a series of physical tests to determine its operating parameters. These are then used to define appropriate boundary conditions for, and evaluate the results from a CFD simulation. Numerous configurations are analysed to explore the effects of different simplifications. From this it was found that the simulation could be considerably streamlined with no consequence for the reported thermal behaviour of the system. In particular the results have shown that modelling of the individual heat sources as discrete loads offered very little benefit except when the sources occupy a region considerably smaller than that of a single distributed load and the systems thermal resistance is also relatively large.