Characterization and optimization of a three dimensional T-type micromixer for convective mixing enhancement with reduced pressure loss

Numerical simulations and experiments are used to evaluate the flow and mixing characteristics of a proposed convective 3-D T-type micromixer. The study presents a parametric study and performance optimization of this micromixer based on the variation of its geometry. To investigate the effect of design and operation parameters on the device performance, a systematic design and optimization methodology is applied; it combines Computational Fluid Dynamics (CFD) with an optimization strategy that integrates Design of Experiments (DOE), Surrogate modeling (SM) and Multi-Objective Genetic Algorithm (MOGA) techniques. The degree of mixing and the pressure loss in the mixing channel are the performance criteria to identify optimum designs at different Reynolds numbers (Re). The convective flow generated in the 3-D T-type micromixer drastically enhances mixing at Re > 100 by making the two fluids to roll up along the mixing channel. The resulting optimum designs are fabricated on polymethylmethacrylate (PMMA) by CNC micromachining. Experiments are carried out to visualize the streams of deionized water and aqueous fluorescein solution, by which the extent of mixing is determined, based on the standard deviation of fluorescein intensities on cross-section images. This study applies a systematic procedure for evaluation and optimization of a proposed 3-D T-mixer which has a configuration of channels that promote convective mixing since the two fluids come into contact. The methodology applied can also be used to efficiently modify and customize current micromixers.