Capsule Migration and Deformation in a Converging Micro-Capillary

The lateral migration of elastic capsules towards a microchannel centerline plays a major role in industrial and physiological processes. Via our computational investigation, we show that a constriction connecting two straight microchannels facilitates the lateral capsule migration considerably, which is relatively slow in straight channels. Our work reveals that the significant cross-streamline migration inside the constriction is dominated by the strong hydrodynamic forces due to the capsule size. However, in the downstream straight channel, the increased interfacial deformation at higher capillary numbers or a lower viscosity ratio and lower membrane hardness results in increased lateral cross-streamline migration. Thus, our work highlights the different migration mechanisms occurring over curved and straight streamlines.

Automated summary

The study reveals that a constriction connecting two straight microchannels significantly facilitates lateral capsule migration compared to straight channels. Different migration mechanisms occur under different conditions, with increased interfacial deformation leading to increased lateral cross-streamline migration in downstream straight channels.