Numerical investigation of the secondary flow effect of lateral structure of micromixing channel on laminar flow

Micromixing remains challenge for microfluidic applications. The outward lateral structure on micromixing channel has been adopted as a mild way to promote micromixing at low Reynolds condition. Herein, this paper presents the numerical investigation of secondary flow effect generated by lateral structure on laminar flows. The velocity difference between the lateral structure and the main channel is the necessary condition for generation of Dean Vortex. Especially, when the velocity difference along the main channel is small and the velocity difference perpendicular to the main channel is large, the greatest secondary flow effect would be generated. The optimal secondary flow effect was obtained through adjusting the size of semicircular lateral structure. The mixing enhancement resulted from lateral structure only showed advantage at Re = 1-4. The semicircular lateral structure was respectively applied to T-shape, Zig-zag and Spit and Recombine micromixers. Remarkable mixing enhancement was observed for both T-shape and Zig-zag serpentine mixer but little promotion for Spit and Recombine micromixer. The square wave serpentine micromixer with lateral structure was successfully utilized for preparation of liposome nanoparticle. This paper reveals the impact factors of the lateral structure on the micromixing process, and indicates the suitable micromixer category for lateral structure application.