Numerical Analysis\nof Controlled Droplet Formation\nSurrounded by a Shear-Thinning Fluid in a Coflow Microfluidic Device

In this work, we used a coupled level set and volume\nof fluid (CLSVOF)\ncomputational method for studying the generation of microdroplets\nin a two-dimensional circular coflow microfluidic device. The fundamental\nunderstanding of shear-thinning behavior on controlled droplet formation\nin a microchannel is systematically investigated. Droplet generation\nand dynamics are controlled by altering the operating conditions and\nfluid properties, such as CMC solution concentration, both fluids’\nflow rates, and interfacial tension. The droplet length, velocity,\nliquid film thickness, and formation frequency are quantitatively\nanalyzed and presented in a non-dimensional form. The droplet length\ndecreased with the flow rate and concentration of the CMC solution.\nHowever, the length of the droplet increased with the dispersed phase\nflow rate and interfacial tension. From the set of simulation data,\nflow regime maps and scaling relations are developed over a range\nof operating conditions. This work provides critical insights into\nthe uniform and controlled droplet formation in shear-thinning fluids\nwithin a circular coflow microchannel, offering guidance for future\ninnovations in the design and optimization of microfluidic systems\nfor specific applications.