| Summary: | Liquid microjet impingement cooling has shown the potential to be the solution for heat removal from electronic devices such as very-large-scale integration (VLSI) chips. The post-impingement dynamics of the jet, specifically the interaction between the liquid fronts on the surface engendered by the jets is a critical criterion improving the heat transfer characteristics. While some seminally important experimental studies have investigated this attribute, the amount of accurate data and analysis is limited by the shortcomings of real-life experiments. In this article, numerical investigations into the fluid dynamics and heat transfer in microjet cooling systems are carried out. Specifically, this paper addresses the question regarding the necessary fidelity of the simulations. Different Reynolds-averaged Navier−Stokes (RANS) models are compared to the Large Eddy Simulations (LES) simulation and the potential fidelity of different eddy-viscosity-based closures is clearly shown. Recommendations are made regarding the RANS closures that should give the best performance. It is demonstrated that the transition Shear Stress Transport (SST) model and <inline-formula> <math display="inline"> <semantics> <mi>k</mi> </semantics> </math> </inline-formula>-<inline-formula> <math display="inline"> <semantics> <mi>ω</mi> </semantics> </math> </inline-formula> SST model both show excellent ability to predict the local or average Nu, and also local level pressure coefficient <inline-formula> <math display="inline"> <semantics> <mi>f</mi> </semantics> </math> </inline-formula> with less than 5% difference in the range of 30 < Re<sub>d</sub> < 4000, compared with the reference LES model. For the experimental measurements in the range of 130 < Re<sub>d</sub> < 1400, the LES model, transition SST model and <inline-formula> <math display="inline"> <semantics> <mi>k</mi> </semantics> </math> </inline-formula>-<inline-formula> <math display="inline"> <semantics> <mi>ω</mi> </semantics> </math> </inline-formula> SST model all show less than 25% prediction error. Moreover, it is shown that the validity of the unit cell assumption for the temperature and flow distribution depends on the flow rate.
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