Analytical model of plug flow in microchannels

Plug flow in microchannels is of great importance in microfluidics as it offers many advantages over continuous-flow microfluidics for various applications of lab-on-a-chip platforms. By confining fluids in small plugs of nanoliter scale, recirculation is formed. To increases our understanding of the flow pattern within liquid plugs, an analytical model of liquid plugs moving in microchannels is presented in this paper. The flow field is obtained by solving partial differential equations with corresponding boundary conditions in the microchannel. The comparison with experimental results from micro particle image velocimetry shows reasonable agreement. The model presented in this paper can be used to predict the flow pattern within liquid plugs, and it is helpful for vortex pattern manipulation in various applications of droplet-based microfluidics.