An Onset of Micromixing Flow Utilizing Marangoni Force

Many kinds of micromixer have been proposed and studied in this decade. The mixing mechanism of most of them has been mainly dependent on molecular diffusion. Therefore, adopting small diffusive distance has been primary measure of mixing enhancement. In this study, we have investigated a novel mixing process with two liquids having difference in surface tension, by the onset of Marangoni effect. Marangoni effect is typical phenomenon on gas-liquid free interface when there is the variation in surface tension. We conducted basic experiments in a microchannel using an air-bubble surface as the gas-liquid interface for the onset of Marangoni covection. We also performed CFD simulation to compare with the experiments. In the experiments, we successfully observed vortex flow which can contribute to species mixing, on the bubble in a few seconds after the moment of contact of the two liquids. Moreover, the CFD simulation could reproduce the vortex flow successfully.