Numerical investigation of cross-connected alternating converging-diverging channels

The thermal and hydraulic performances of an air-cooled heat sink channel design have been numerically investigated in 2D computational domains in ANSYS Fluent. The channel expansion ratio (ER) is the key parameter to control the flow restriction, therefore the rate of flow mixing. As the channel ER is increased, Nu number increases with an accompanying increase in the pressure drop penalty. The heat transfer enhancement is attributed to two main phenomena: flow mixing, and thermal boundary layer (TBL) disruption and reinitialization. Thanks to flow mixing, air temperature builds up more uniformly in the direction of flow and TBL disruption and reinitialization decreases the thermal resistance on the channel walls. Despite the increase in the pressure drop penalty with increasing channel ER; it is possible to enhance thermal resistance by 40% with the same pressure drop of a straight channel heat sink. (C) 2015 The Authors. Published by Elsevier Ltd.