Mixing in a drop moving through a serpentine channel: A computational study

The chaotic mixing in a drop moving through a winding channel is studied computationally in a two-dimensional setting. The molecular mixing is ignored and only the mixing due to the chaotic advection is considered. Passive tracer particles are used to visualize the mixing patterns and mixing is quantified by two distinct methods. It is found that both the quantification methods are consistent with visual observations as well as with each other. The effects of various non-dimensional parameters on the quality of mixing are studied and it is found that the capillary number, the ratio of the drop phase fluid viscosity to that of the ambient fluid and the relative size of the drop compared to the average channel width are the most critical parameters influencing the mixing. The mixing is found to be weakly dependent on Reynolds number.