The problem of viscous resistance significantly hinders the development of effective microsystems for industrial applications, such as chemical analysis and cooling of microelectronics. We present results of experiments and three-dimensional numerical simulations of fluid flow in a rectangular smooth-walled microchannel with a hydraulic diameter of 149 μm. A pressure drop is measured, which depends on the flow rate and temperature of the inlet liquid. To examine the effect of fluid properties, three different liquids are tested, namely, water, ethanol, and methoxynonafluorobutane. The Reynolds number depends on temperature and is varied within the range 68-3011. It is found that the temperature dependence of the liquid viscosity can be used to significantly reduce the pressure drop along the channel. Heating the inlet fluid enables the pressure drop to be reduced by up to 40%. Based on the experimental measurements of the pressure drop in the fluid flow, the wall shear stress is found numerically, thereby allowing correlations to be obtained for the friction factor. The results show that the wall shear stress for numerical simulations can be estimated using the friction factor from the well-known formula with a slight deviation at a high Reynolds number. The experimental results are also in good agreement with the theoretical data for conventional channels.
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