Application of low-Reynolds number turbulent flow models to the prediction of electronic component heat transfer

Abstract

The turbulent flow modeling capabilities of Computational Fluid Dynamics (CFD) codes dedicated to the thermal analysis of electronic equipment are typically constrained to zero-equation mixing length and standard two-equation high-Reynolds number k-e eddy viscosity models. Recent publications have highlighted their potential shortcomings for the prediction of electronic component heat transfer. Using experimental benchmarks, this study investigates the performance of alternative, low-Reynolds number eddy viscosity turbulent flow modeling strategies. Significant improvements in component operating temperature prediction accuracy are obtained relative to the standard high-Reynolds number k-e model. For the test configurations considered, improved predictive accuracy is attributed to the greater suitability of the near-wall turbulence modeling employed for the prediction of heat transfer in reattaching or separating flow conditions, as compared to turbulence models relying on wall functions. Such improvements would enable parametric analysis of product thermal performance to be undertaken with greater confidence, and contribute to the generation of more accurate temperature boundary conditions for electronics reliability assessment. This could ultimately help reduce the current dependency on experimental prototyping. The case is made for vendors of CFD codes dedicated to the thermal analysis of electronics to consider the adoption of eddy viscosity turbulence models more suited to detailed board-level analysis than the standard high-Reynolds number k-e model.