In this numerical study the the heat transfer and laminar nanofluid flow in the three-dimensional microchannels with triangular cross-section is simulated. For increase the heat transfer from the walls of the channel, semiattached & offset mid- truncated rib,s Placed in the canal, and the tooth geometry and the impact is studied. In this study, the water is base fluid, and the influence of the volume fraction of nanoparticles of titanium oxide on the the heat transfer and the fluid flow physics is studied. The presented results include the distribution of Nusselt number in the channel, The coefficient of friction and the thermal-fluid performance for each of the different states. The results show the existence of is the tooth on the effective flow physics. And their efficacy is highly dependent on Reynolds number. Use indentation in the microchannels, increase the heat transfer rate and the reduce the temperature gradient between the layers of the cooling fluid. Also, the presence of nanoparticles in the fluid cooling is effective and the pain increase the heat transfer by increasing the Reynolds number, the effect of nanoparticles also increase the heat transfer increases. تفاصيل المقالة