Fluid flow and mixing characteristics in micromixer with vortex-generated structures

A design for modified planar passive micromixer based on the concept of vortex-generated structure enhanced mixing is described in this work. By using computational fluid dynamics CFD-ACE+, three-dimensional numerical simulation and structural optimization for mixing were performed in order to reveal the structural influence on the flow feature and mixing characteristics. Experimental data were used to validate the numerical analysis. The computational and experimental results for the concentration distributions and flow patterns demonstrate that the expansion vortices, separated vortices and Dean vortices appear in the curved channel of this modified micromixer, which is arranged to vortex-generated structures. The combination and enhancement of the vortex system increase the fluid disturbance, effectively improving the contact area of fluid and accelerating the mixing process. Based on comprehensive consideration of mixing efficiency and pressure drop distribution, the structural design adopts the vortex-generated structure with regular arrangement, and the gap width ratio W_d/W, thickness-width ratio B/W, and arrangement angle θ_a are equal to 1/4, 3/10, and 120°, respectively. Significant mixing effect of fluid in the micromixer can be realized in a wide range of Reynolds number.