Design of single-wave-based curved and rectangular serpentine microchannels for mixing applications: a CFD study

Abstract Microchannels are critical components in microfluidics, enabling efficient and controlled mixing of two miscible fluids by utilizing unique microscale fluid dynamics. The design of these microchannels significantly affects mixing performance, influencing the extent, speed, and uniformity of mixing, which are vital for the success of various lab-on-chip and biomedical applications. Numerical simulations were conducted to examine the flow and mixing characteristics of single-wave serpentine microchannels with both curved and rectangular geometries. The micromixer configurations consisted of a single-wave serpentine channel coupled with five mixing chambers. COMSOL Multiphysics, an FEM-based software, was used to simulate the mixing performance of the micromixers. A total of eight distinct single-wave serpentine channel designs were evaluated across a Reynolds number range of 0.1–60. The effects of Reynolds number, channel shape (curved versus rectangular), and the form of obstacles on mixing efficiency and pressure drop were assessed. The results indicate that Re = 5 as a critical transition point where mixing shifts from diffusion-dominated to advection-enhanced behavior. Among the eight designs analyzed, the rectangular wave serpentine channel with angle-shaped obstacles demonstrated superior performance, achieving over 80 % mixing efficiency, making it a promising candidate for lab-on-a-chip applications. Findings indicate that micromixers with rectangular wave serpentine channels exhibit higher mixing efficiency than those with curved wave designs. These configurations show strong potential for chemical applications requiring rapid and effective mixing.