## 4 Concluding Remarks  
The present work comprehensively investigated the impacts of different straight microchannel geometry designs of heat sinks on the flow and heat distribution throughout the channels via numerical modeling. The simulations were performed with the conjugate heat transfer module ofthe software _COMSOL Multiphysics 5.6_. From the different relative positions of the inlet and outlet that were tested, the vertical placement allowed the development of a flow with greater uniformity, while the frontal placement showed the highest flow maldistribution. The results also showed that the collector with a rectangular  
Figure 23: Heat transfer rate in each channel of the geometries: (**a**) Vertical rectangular. (**b**) Horizontal parallel. Figure 22: Temperature profiles for the studied configurations for heat transfer at a flow rate of 5 mL/min: (**a**) Vertical Rectangular with 8 channels; (**b**) Vertical Rectangular with 6 channels; (**c**) Horizontal Parallel with 6 channels. shape was the one leading to greater uniformity, while the triangular shape led to the least uniformity since the geometry causes a disturbance in the jet impingement. Additionally, this study indicates that increasing the number of channels tends to improve the uniformity of the flow distribution. In this way, the microchannel heat sink that showed the greatest flow uniformity and heat transfer performance was the heat sink with the vertical placement of the inlet and outlet, a rectangular collector, and eight microchannels. So, as the main concluding remark, the following guidelines for obtaining an optimized microchannel heat sink design, which is essential to providing high heat dissipation rates, should be considered:  
* A rectangular-shaped collector, since this causes less flow maldistribution and instability. * Vertical placement of the inlet and outlet, since, in the particular case of the inlet, this causes less throttling and the easier breaking and spreading of the impinging jet. * The maximum number of microchannels possible within the limits of the intended overall reduced dimensions of the heat sinks (eight in the case of the current work). These guidelines, together with the results obtained in this work, highlight the key role played by the optimization of the geometrical arrangement of thermal management devices. Scaling down from macro- to micro-devices entails several issues related to the flow rate and the distribution that must be considered. The most preeminent practical impact of this work is the guidance offered for the design and production of more efficient and cost-effective miniaturized devices, such as micro channel heat sinks, which seem to be the most reliable thermal management technology due to their command of heat transfer capability. In future work, it will be important to compare the results to experimental models, and also to test, numerically and experimentally, the flow of nanofluids in microchannel heat sinks with an optimized design. Conceptualization, A.S.M., J.M.M., C.R., R.R.S. and R.L. ; methodology, A.S.M., J.M.M., C.R., R.L. and R.R.S. ; formal analysis, A.S.M., J.M.M., C.R., R.R.S. and I.M.G. ; investigation, A.S.M., J.M.M., C.R., R.R.S., I.M.G., J.E.P. and G.C., resources, A.S.M., J.M.M., R.L., R.R.S. and A.L.N.M., data curation, C.R., R.R.S. and I.M.G., writing-original drafting preparation, A.S.M., C.R., R.R.S., I.M.G., J.E.P., writing-review and editing, A.S.M., J.M.M., C.R., R.R.S., R.L., J.E.P., A.L.N.M., G.C. ; visualization, A.S.M., J.M.M., C.R., R.R.S., supervision, A.S.M., R.L. and J.M.M. ; project administration, A.S.M., R.L., J.M.M. and A.L.N.M., funding acquisition, A.S.M., R.L., J.M.M. and A.L.N.M. All authors have read and agreed to the published version of the manuscript. This research received no external funding. Not applicable.