<p>A series of conjugate heat transfer simulations were performed to examine the effects of geometrical modifications and different grooves arrangement on the fluid flow and heat transfer characteristics of coolant flow in microchannel heat sinks containing water-droplet grooves. Numerical investigations were then conducted on the microchannel heat sinks which incorporate the water-droplet grooves for a primary channel inlet velocity in the range of 0.2–1.0&#xa0;m/s. The presence of water-droplet grooves is found to yield better thermo-hydraulic performance, in comparison with the conventional microchannel heat sink. Using this novel design, the reduction in the thermal resistance is revealed to be more than triple than the increase in the pumping power needed. Based on the simulation results, it is inferred that staggered grooves arrangement would yield a better overall performance, as compared with that of in-line grooves arrangement. In addition, the effects of groove pitch length modification on the fluid flow and thermal are explored, along with the assessment of the aspect ratio influence on the thermo-hydraulic performance. To achieve better heat dissipation, it is preferable to have a shorter groove pitch length and a larger groove aspect ratio of the water-droplet grooved microchannel heat sink.</p>