Design and analysis of a novel Bi-layer curved serpentine chaotic micromixer for efficient mixing

Mixing enhancement at the micro-scale is important in microfluidics applications, including biological and chemical analysis systems. Herein, two new designs of chaotic micromixers named Bi-layer Curved Serpentine (BCS1 and BCS2) micromixers were proposed. The performance analyses were performed by solving the steady equations of conservation of mass and momentum along with the convection-diffusion equation numerically at Reynolds numbers of 0.1-200. These micromixers consisted of curved serpentine channels stacked in two layers with different combinations of curved channel radii in each layer. They exhibited efficient homogenization with a comparatively lower pressure drop and a higher mixing cost. The main mixing processes were Dean vortices, extensional flow, and chaotic advection caused by asymmetrical vortices. The BCS1 micromixer, which has a constant but unequal radius of the serpentine channel in the top and bottom layers, showed the best mixing. BCS1 and BCS2 micromixers showed significantly higher mixing indices than the simple serpentine (SS) micromixer. Furthermore, the BCS1 micromixer provided a higher mixing cost by showing similar mixing at a similar to 53% lesser pressure drop than a previously proposed serpentine micromixer. BCS1 and BCS2 micromixers showed mixing index values higher than 0.80 at Re >= 40 and Re >= 60, respectively.