Laminar Fluid Mixing in Micromixers: Description of Pull‐Push Effects

A numerical study was performed on laminar mixing of fluids by means of embedded microbarriers against the flow direction in two three‐dimensional T‐micromixers. Two microchannels with different obstacle arrangements were considered, and the effect of volumetric flow rate Q on two‐stream pull‐push motion was investigated. With increasing Q and distance of the barriers to the sidewalls K, different vortices and fluid movement patterns develop in the two micromixers. Maximum mass transfer is obtained for the micromixer with smaller K value. With decreasing K, pull‐push movement strongly affects fluid merging, and the quality of mixing increases. Moreover, the effect of fluid tortuosity was studied, and a direct relationship between hydrodynamic fluid tortuosity and mass transfer was found. Microfabricated devices are attractive for various chemical engineering applications. Herein, a micromixer was designed by numerical simulation, and the effect of cylindrical barriers on the fluid tortuosity was studied. The relation between fluid tortuosity and mass transfer and the effect of pull‐push phenomena of fluids on the mixing index due to the presence of microbarriers were studied.