T-shaped micromixers aligned in a row: characterization of the engulfment regime

Accurate control of mixing between two fluids is a fundamental aspect in many applications and generally implies the use of small devices operating at low velocities. This is often achieved using micromixers which, due to the combination of small dimensions and low velocities, work in the laminar regime and generally process very limited flow rates. The flow rates can be increased using more mixers at the same time. In this respect it is appealing to use several micromixers connected in a unique device. In this paper we propose and characterize a simple strategy to connect several T-mixers together by aligning them in a row and feeding them by shared inlet channels. Since engulfment is the preferred flow regime for mixing, we investigate the proposed devices specifically focusing on the onset and on the properties of the engulfment regime. This investigation is carried out by a combined use of numerical simulation and linear stability analysis. The results reported here show that the proposed strategy can lead to compact devices in which the single mixers manifest engulfment, although some important differences in comparison with isolated T-mixers may exist depending on the spacing between the inlet/outlet channels in the device.