Numerical analysis of a microfluidic mixer and the effects of different cross-sections and various input angles on its mixing performance

Abstract

Micromixers have better efficiency in terms of both the time-scale of chemical kinetics and diffusive transport compared to the conventional macro-mixers. The mixing efficiency in micromixers is an important performance indicator in mixers. This paper presents a numerical study of how the design of a micromixer along with the design of the mixing process affects the mixing efficiency. Specifically, two different types of cross-sections of the channel in micromixers, namely circular and rectangular cross-sections, together with the inlet angle of the channel, were studied. The process parameters, such as the inlet velocity of fluids and diffusion coefficient, were studied as well. The result shows that the circular cross-section can sustain a large pressure difference without undergoing any remarkable distortion and deformation, and it can achieve better performance. The result further indicates that the inlet velocity and diffusion coefficient have significant effects on mixing efficiency; specifically, the low inlet velocity and high diffusion coefficient value can lead to a better mixing performance. However, different input angles alone could not make the mixing efficiency change noticeably. In other words, the mixing performance of such micromixers relies more on the inlet velocity and diffusion coefficient than on the fluid flow angle in the inlet.