Fluid flow and heat transfer in microchannel heat sinks with zigzag longitudinal fins

Laminar fluid flow and conjugate heat transfer in three-dimensional microchannels have been examined by carrying out simulations for heat sinks with zigzag fins. The coolant water velocity distribution showed that the fin peaks cause circulation of the flow that form mixing. The pressure distributions illustrate a nonlinear change with the axial location as pressure jumps occur at the fin peaks. The plot of developing Nusselt number shows repeated pattern resulted from periodic change of the flow direction. The heat transfer coefficient was found to be distinctly enhancing as the fin wave height increases. The resulting maximum heat transfer coefficients were as high as 200, 000 W/(m² K), however with considerably higher friction factors at Re = 300. The jumps in the local Nusselt number evidenced the changes in fluid flow pattern as the zigzag fins provide mixing due to secondary flows and repeated growth and destruction of the boundary layers.