Comparative Analysis of Passive Micromixers at a Wide Range of Reynolds Numbers

Abstract

Two novel passive micromixers, denoted as the Y-Y mixer and the H-C mixer, based on split-and-recombine (SAR) principle are studied both experimentally and numerically over Reynolds numbers ranging from 1 to 100. An image analysis technique was used to evaluate mixture homogeneity at four target areas. Numerical simulations were found to be a useful support for the design phase, since a general idea of mixing of fluids can be inferred from the segregation or the distribution of path lines. Comparison with a well-known mixer, the Tear-drop one, was also performed. Over the examined range of Reynolds numbers 1 ď Re ď 100, the Y-Y and H-C mixers showed at their exit an almost flat mixing index characteristic, with a mixing efficiency higher than 90%; conversely the Tear-drop mixer showed a relevant decrease of efficiency at mid-range. Furthermore, the Y-Y and the H-C showed significantly less pressure drop than the Tear-drop mixer.

Numerical study of fluid mixing at different inlet flow-rate ratios in Tear-drop and Chain micromixers compared to a new H-C passive micromixer

“…A SIMPLEC scheme was assigned as the solution method used to calculate pressure velocity coupling (Mansur, Wang, & Dai, 2008). The secondorder upwind schemes of momentum and pressure were used to achieve a more accurate solution (Viktorov et al, 2015).…”

“…One of the SAR mixers, namely the Caterpillar, has been successfully employed for many industrial applications at high Reynolds numbers; nevertheless, its mixing ability is of minor quality in the case of Reynolds numbers below about 500 (Schönfeld, Hessel, & Hofmann, 2004). In fact, according to the literature, most of the micromixers have satisfying operation at either high or low Reynolds numbers -and SAR micromixers in particular have high energy requirements because of their complex structure (Viktorov, Mahmud, & Visconte, 2015). Therefore, the development of high-performance devices that can work over a wide range of Reynolds numbers with an acceptable pressure drop is currently a major focus of research.…”

Computational Design and Experimental Validation of SAR Mixers

“…As the Reynolds numbers increase, there is a shorter residence time for the fluid particles to diffuse, and as a result worse mixing efficiency could be expected. Nevertheless, the Y-Y and the H-C mixers show good efficiency due to the three-dimensional change of direction of flow in the input of each element, which promotes a helical fluid motion; as a consequence, the fluid path is lengthened [13]. However, this swirling effect is less evident in the Chain mixer.…”

“…SAR mixers show good mixing efficiency at low Reynolds number (Re<20) and high Reynolds number (Re>100), whereas mixing performance is relatively low at middle range [13]. Two novel SAR mixers, namely the Y-Y and the H-C, are developed and studied at Reynolds numbers ranging from 1 to 100.…”

Microfluidic 3D Helix Mixers

“…Other geometries are presented in ( d ) the Teardrop, ( e ) the Y–Y and ( f ) the H–C mixing geometries at Re = 1 ( top ), 30 ( middle ) and 100 ( bottom ). The left column of each geometry represents an experiment, where as on the right the images taken from computer simulations (with permission from Vladimir Viktorov [ 11 ]). ( g ) The herringbone mixer, ( h ) a double helix and ( i ) a triple helix mixer.…”