On the computational analysis of short mixing length planar split and recombine micromixers for microfluidic applications

Micromixers are one of the prominent devices in applications like Lab-On-A-Chip (LOC), micro-total analysis system (mu TAS), etc. The performance of micromixer is governed by geometry of micromixer, type of obstructions like baffles, obstacles introduced in the fluid flow. In this paper, the mixing performance for three types of baffle-based split and recombination planar passive micromixers is analysed using numerical simulation. The three design configurations, namely, square baffle-based split and recombination (SB-SAR), circular baffle-based split and recombination (CB-SAR) and triangular baffle-based split and recombination (TB-SAR) micromixers are considered. In-depth flow physics analysis was carried out to assess and affirm the quantitative results of the mixing quality at Reynolds number in the range of 0.1-60. The mixing index is found to be 1.0 at Re = 0.1 for SB-SAR micromixer and 0.80 at Re >= 10 for all the micromixer design configurations. Micromixers showed diffusion-dominated mixing mechanism at Re = 0.1, and chaotic advection dominated mixing mechanism at Re >= 30. The advantages of rapid mixing, simple geometry and shortest mixing length make these micromixers more encouraging in chemical, biochemical and medical applications.