Background: Mixing of fluids and reagents at the micro level is a very crucial phenomenon
for various microfluidic applications.
Objective: This work focuses on the analysis of serpentine micromixers and various design modifications
of them for faster and better mixing purpose.
Method: CFD simulations of the designed micromixers have been carried out at an ultra-low Reynolds
number region (Re < 0.25). The designs are modified by incorporating obstacles on their walls in terms
of different obstacles. Also a new design of micromixer, the garland micromixer is proposed and its micromixing
performance characteristics are evaluated.
Results: Numerical analyses with COMSOL Multiphysics reveal that placing obstacles to the flow in
the micromixer can enhance the mixing process significantly. Rectangular shaped obstacles give the better
mixing results than the triangular shaped obstacles; on the other hand the triangular shaped obstacles
are associated with the least pressure drop among the protruded geometries of the serpentine micromixers.
Moreover, the layout having obstacles placed at the mid horizontal portion is giving better mixing
as compared to placing obstacle of same size and shape at the corners. Study shows that the mixing efficiency
increases as the length of the obstacle increases with a slight deviation as in the case when the
obstacles form symmetrical structure with another design element.
Conclusion: The proposed garland design of micromixer is found to be better than the existing serpentine
designs for micromixing. These designing concepts can be further explored in conjunction with
other flow manipulation techniques for getting enhanced mixing performance.