Numerical and experimental study on the synergistic effect of vortex and contact surface of fluid in the inlet section of micromixer

The promoting effect of vortex on the mixing performance of micromixer is difficult to be quantitatively evaluated. In this study, the concept of flux across line (FAL) is proposed for the first time to quantitatively analyze the influence of synergistic effect between the vortex and the contact surface of fluid on the mixing. The FAL value of T-shaped and cross-shaped micromixers is obtained by integrating the velocity component after decomposing the velocity vector on the cross section of the straight channel. The intensity distribution and development of vortex in the inlet section are quantitatively revealed by numerical simulation at Re = 50. Ac-cording to the FAL analysis, a two-layer feed T-shaped micromixer (TLFT-shaped) is designed to verify the effective synergy between vortex and contact surface of fluid. The FAL value of TLFT-shaped is 40-50 % higher than that of cross-shaped, the promoting effect of vortex on mixing is reflected in the mixing index, which experiences a notable 56 % increase. The concentration distributions of visualization experiments and simulations are consistent, which proves the accuracy of simulation results. The FAL analysis can quantitatively evaluate the promotion effect of vortex on mixing, which provides valuable guidance for the design of microfluidic devices.