Abstract: The geometric effects on the liquid flow are investigated in microchannel based on the numerical simulation method. Effects of geometry are shown obviously on the microflow by comparing the results of different geometric characteristics covered hydraulic diameter, length and aspect ratio. Thermal boundary conditions are same for different cases in the numerical simulation. The effects of geometric parameters on the Poiseuille number and the Nusselt number are investigated. The Poiseuille number decreases with the increasing of the aspect ratio while the Reynolds number has no effect on it for the same aspect ratio microchannels. For Re<500, when the hydraulic diameter Dh<0.545 mm, Po decreases with the Dh, but Po does not change when Dh is larger. The length of the microchannel has no effect on Po while Reynolds number has a little influence on it. When Re is 20-1 800, Nu is proportional to the hydraulic diameter and aspect ratio of the microchannel. Effects of the length on the Nusselt number vary at different Reynolds number. The relation of Nu and Re can be fitted, which is affected by the geometry of microchannels for the same substrate and flow liquid.

Key words: Flow, Geometry, Heat Transfer, Microchannel