Towards efficient micromixing by synthetic vortical structures

A new active strategy is proposed to enhance mixing in microfluidic systems. Staggered perturbations in the spanwise direction are imposed to the flow and the scalar transport is analysed by direct numerical simulations of high temporal and spatial resolution. The aim is to produce turbulent-like stretched synthetic vortical structures that are the best in terms of mixing enhancement. It is shown that such structures can indeed be regenerated at significantly low Reynolds numbers through maintained perturbations periodical in time. The specific interactions asymmetrically distributed in space lead to a better mixing, in particular locally in time and space leading to the possibility of active control of scalar transport in microdevices.