Fluid and heat transfer characteristics of microchannel heat sink with truncated rib on sidewall

•The TRs could reduce the pressure drop penalty without heat transfer loss.•Compared with the CR, the TR provides the better overall thermal performance.•The effects of geometry parameters on the hydrothermal performance are analyzed. Flow and heat transfer characteristics of a microchannel heat sink (MCHS) with truncated ribs (TRs) on the sidewall are studied numerically for Reynolds number ranging from 100 to 1000. Three parameters of the TR configuration -gap height, rib arrangement and rib width - are selected to analyze the effects of rib geometry on the hydrothermal performance. It is found that, either in the staggered cases or parallel cases, the TRs can improve the heat transfer near the truncation gap and decrease largely overall pressure drop. Therefore, the existence of TR can improve the overall thermal performance by reducing the pressure drop penalty without heat transfer loss. As the truncation gap increases, the larger pressure drop penalty can be reduced by increasing the flow area.