Two-phase flow patterns and size distribution of droplets in a microfluidic T-junction: Experimental observations in the squeezing regime

What is it about?

Generating micrometer sized droplets has been studied in a microfluidic system with T-junction geometry 250 μm in internal diameter and with PTFE capillary tubing. Several experiments were conducted by varying the flow rate of the dispersed phase from 2.78⋅10−11 m3/s to 5.28⋅10−9 m3/s and that of the continuous phase from 2.78⋅10−10 m3/s to 1.94⋅10−9 m3/s. The visualization of different flow regimes (drop, plug, and annular) was carried out for three configurations (not inverted in a horizontal position, inverted in a horizontal position, and inverted in a vertical position) for low capillary numbers. The model of Gauss was also chosen for a droplet size distribution in the dispersed phase, with the flow quality x varying from 0.016 to 0.44. The evolution of the drop size distribution as a function of the flow quality in the dispersed phase shows that the variation coefficient of the droplet's diameter is inversely proportional to the flow quality.

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Why is it important?

The present work aims to contribute to a better understanding of the two-phase flow of two immiscible liquids in a T-junction-shaped microfluidic system. In the first part of this work, we describe the experimental set-up used to study the two-phase flow in the microfluidic system with different orientations of the T-junction and the method used for deducing the diameter of the drops followed by the results obtained in the visualization of the different flows regimes (annular, plug and drop) for each orientation of the T-junction.