Drag-induced breakup mechanism for droplet generation in dripping within flow focusing microfluidics

Based on viscous drag-induced breakup mechanism, a simple model was proposed to predict the dripping droplet size as a function of controllable parameters in flow focusing micro devices. The size of thread before breakup was also investigated through laminar flow theory. Experiments and numerical simulations by VOF are carried out simultaneously to validate the theoretical analysis, showing that droplet size decreases rapidly with the increase of the flow rate ratio and capillary number.

Graphical abstractA viscous drag-induced breakup mechanism is proposed to predict the droplet size as a function of controllable parameters. The results of the final droplet size prediction is in remarkable agreement with the experimental measurements and numerical simulations, suggesting that higher flow rate ratio and capillary number will generate smaller emulsion droplets in dripping regimes. This theoretical analysis shows that droplet size in flow focusing microfluidics is predictable and controllable, which is meaningful for the control of droplet formation, operating condition selection and the microfluidic geometry excogitation.Figure optionsDownload full-size imageDownload as PowerPoint slide