Single-phase fluid flow and mixing in microchannels

In the last decade there has been an exponential increase in microfluidic applications due to high surface-to-volume ratios and compactness of microscale devices, which makes them attractive alternatives to conventional systems. The continuing growing trends of microfluidic highlights the importance to understand the mechanism and fundamental differences involved in fluid flow and mixing at microscale. In the present article, the experimental research efforts in the area of microscale single-phase fluid flow and issues associated with investigations at microscale flow have been summarized. The experimental data are being analyzed in terms of friction factor, laminar-to-turbulent transition, and the effect of roughness on fluid hydrodynamics for different cross-sectional geometries. The differences in the uncharacteristic behavior of the transport mechanisms through microchannels due to compressibility and rarefaction, relative roughness, property variations and viscous dissipation effects are discussed. Finally, progress on recent development of micromixers has been reported for different micromixer types and designs. The micromixers have been quantified based on their operating ranges (in terms of characteristic dimensionless numbers such as Reynolds number Re, Peclet number Pe, and Strouhal number St) and mixing characteristics.