Activity-Induced Mixing in a Stratified Binary Passive System

Active systems have garnered interest from researchers worldwide for their fascinating displays of congregations and the far-reaching scope of biomimetic applications. The current chapter talks about one such application: the use of active particles to induce mixing in a stratified passive system. Simulations using a Langevin model in two dimensions shows the mixing state of the initially stratified system reach a saturation point in finite time. Interestingly, with change in the number of active mixers, only the rate of mixing is found to be affected, while the final mixed state is perceived to be almost similar. Active particles numbering not more than 20% of that of the passive species is found to be enough to induce brisk mixing. An investigation is parallelly carried out into the maximum rotation allowed for each active mixer to maximise the overall mixing effect. The objective of this discourse is to provide a numerical backbone to the feasibility of the use of micro/mini robots for mixing of living/non-living entities, while also discussing the factors affecting the process.