Colored particle tracking method for mixing analysis of chaotic micromixers

Abstract

Micromixers have a variety of applications in chemical and biological processes, becoming an important component in microfluidic systems. The present work aims at understanding detailed mixing behaviour of micromixers by developing a numerical analysis scheme, which ultimately facilitates efficient micromixer design. A systematic numerical method has been developed, enabling visualization of detailed mixing patterns and quantification of the mixing performance in chaotic micromixers. The overall numerical scheme is named ‘colored particle tracking method’ (CPTM), consisting of three steps: (i) a flow analysis to obtain a periodic velocity field of a periodic mixing protocol by the Galerkin/least-squares (GLS) method; (ii) a particle tracking step, particles being labeled by a specific color at the inlet according to fluid species, to obtain a distribution of colored particles at the end of the final period; (iii) a quantification of the degree of mixing from the obtained particle distribution. For the last step we propose a new mixing measure based on the information entropy. The CPTM has successfully been applied to three examples of micromixers with patterned grooves to evaluate their mixing performance both qualitatively and quantitatively. The CPTM seems promising as a practically attractive numerical scheme for mixing analysis of chaotic micromixers.

Evaluation of Floor-grooved Micromixers using Concentration-channel Length Profiles

“…To characterize the mixing performance of the micromixers in order to better understand and design more efficient micromixers for different applications, a number of techniques, both experimentally [14][15][16][17][18] and theoretically [12,[19][20][21][22][23][24][25][26][27][28], have been employed. Particularly, CFD has been widely used to study the mixing behavior of micromixers in details.…”

Geometrical optimization of helical flow in grooved micromixers

“…To avoid these numerical errors, several studies have utilized particle tracking methods to characterize the mixing properties of the SHM and SGM in more detail. Kang et al 27 utilized colored particle tracers to display excellent resolution of the multi-cycle SHM mixing profile, Camesasca et al 28 utilized statistical entropy of particle tracers to evaluate the mixing efficiency of the original SHM design, and Aubin et al 29 displayed Poincaré maps for the original SHM and SGM designs in addition to an analysis of the magnitude of the rate of deformation tensor along the length of the mixer.…”

The Effect of Inertia on the Flow and Mixing Characteristics of a Chaotic Serpentine Mixer

“…As seen from its application, in previous studies [17,25,29,30], this proves to be a good assumption when investigating the progress of mixing in a micromixer composed of repeating mixing protocols, each with their own flow characteristics. Thus, the computational domain for the flow and mixing analysis is defined as one periodic unit of the mixer, as shown in Figure 1.…”