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Microchannel heatsinks with porous media, wavy and multi-layered configurations introduce compact designs and high efficiencies in cooling applications. Current Computational Fluid Dynamics (CFD) based study bridges the concept by introducing a novel double layered microchannel heatsink with wavy up-down and porous ribs alongside each other. Since Artificial Neural Network (ANN) trained by CFD results reveals designs with better thermal and hydraulic performance with an insignificant computational time, ANN is employed for finding the best performers and effects of waviness on Nusselt number, pressure drop, and maximum temperature difference at the bottom of the microchannel for a Reynold number range of 100 < Re < 800 by defining a thermal efficiency factor. Even though the pressure drop increases in the wavy design, the thermal performance is affected positively. Nusselt number increases more than 55% for Re = 800. The thermal performance increases with the introduction of Dean vortices, especially at higher Re. The best design provides maximum bottom temperature difference of 1.2 °C, with a Thermal Efficiency Factor of 1.34. However, it is observed that better thermal efficiency factors are attained by using a wavy channel at the top layer and keeping the bottom layer straight for the final design. [ABSTRACT FROM AUTHOR]

Abstract: A computational fluid dynamics methodology is developed to study steady laminar flow and heat transfer in periodic zigzag channels with square cross-sections, considering the effect of chaotic advection. The computational domain consists of up to 14 repeating zigzag units with smoothly joined inlet and outlet sections. The results show fully-developed periodic flow fields can be achieved for Re <200; however, a spatially periodic flow field is no longer seen for higher Reynolds number due to the enhanced effect of chaotic advection with increasing Reynolds number; for Re >400 the flow field becomes transient. The flow field shows that the secondary flow pattern varies significantly at different axial locations. Highly enhanced heat transfer appears in the regions where strong Dean vortices occur, as indicated by more pronounced twisting of flow streaklines. For Re >200, the unit-averaged heat transfer enhancement and pressure-drop penalty (relative to straight passages) are no longer uniform from unit to unit but mean values of both of these performance metrics increase with increasing Reynolds number over the whole range of 50< Re <400. [Copyright &y& Elsevier]