An analytical study of micro-droplet generation in microfluidic double T-junction devices under effects of channel depth ratio using VOF method

This paper describes a numerical study on micro-droplet generation in a microfluidic double T-junction device under the effects of channel depth using the Volume-Of-Fluid method. The effects of various parameters such as capillary number (Ca), water fraction (wf), viscosity ratio \((\beta )\), and particularly the channel depth ratio \((\varepsilon )\) were examined. Consequently, the numerical results match well with the experimental data obtained in the literature. Additionally, the micro-droplet size increases with increasing the channel depth ratio. A phase diagram with four main micro-droplet generation regimes is provided. Particularly, the alternating mode is narrowed in both Ca and wf ranges when increasing \(\varepsilon \). Moreover, four regimes of micro-droplet generation with the presence of channel depth were first discovered in the present study, and the stable micro-droplet generation regime can be gained within an effective range of both \(\varepsilon \) and \(\beta \). These results are very useful and valuable for many applications in emulsion production, hydrogel particle generation, and drug delivery synthesis in biomedical treatment.