Numerical investigations on the effect of multi-dimensional stepness in open micro pin fin heat sink using single phase liquid fluid flow

In present work, the square shaped micro pin fin configuration of microchannel heat sink has been numerically investigated under different geometrical variation. Considering effectiveness of open microchannel, the pin fin height has been varied in two different styles. Firstly, the consecutive pin fins are varied in step of two and three rows. Secondly, the step variations were opted along only the channel length (unidirectional) and along both channel length and channel width (bidirectional). Furthermore, all configurations are having equal convective area so that influence of out of plane mixing can be studied more precisely. Estimated findings clearly indicated that stepped configuration has superior thermo-hydraulic performance compared to uniform configuration due to out of plane fluid motion resulting in enhanced flow mixing. Afterwards, bidirectional step has shown augmented performance compared to unidirectional step heat sink configuration because of enhanced secondary fluid flow and distinct vortices formation behind each pin fins. Among all considered configurations, three stepped bidirectional micro pin fin heat sink has yielded best performance i.e. 28.3% higher heat transfer rate and 2% lesser average bottom wall temperature compared to uniform height pin fin configuration.