Droplets generation under different flow rates in T-junction microchannel with a neck

The 2D top view of the droplet formation in microfluidic T-junction devices with a neck is recorded to estimate the droplet volume under different flow conditions. The channel with a neck at the T-junction, to provide a narrow structure, is proposed but has not been analyzed as the normal T-junction. The droplet generation process is separated into two stages, including the filling stage and the squeezing stage, to develop a droplet size predictive model based on the continuity of both liquids. In a wide range of flow conditions for multiphase microfluidics, this study validates and physically explains the model by analyzing the generation of droplets and coefficients of the model. Results of this study can help to design droplet microfluidic devices, where it is requisite to know the relation between flow conditions and the droplet size.