Simulation of droplet dynamics through micro-orifices in Carreau–Yasuda fluids

A comprehensive numerical investigation is presented in this study to understand the behavior of deformation and transport of droplets through a micro-orifice in Carreau–Yasuda non-Newtonian fluids. The level set method is used to simulate the behavior of the droplet over time. The influence of the orifice geometry, droplet size, and fluid rheology on the spatiotemporal evolution of the droplet interface, pressure, shear rate, and viscosity fields is investigated during the transit of the orifice. The behavior of the interface dynamics alters as various Carreau–Yasuda concentrations are evaluated, demonstrating the influence of shear-thinning behavior on the pressure buildup upstream of the orifice. The simulations reveal that increasing the continuous phase concentration results in a 35% rise in maximum upstream pressure and a 28% increase in peak shear rate due to enhanced shear-thinning behavior. Additionally, larger droplets with more confinement inside the channel experience earlier deformation and sharper fluctuations in aspect ratio compared to smaller droplets, particularly in narrow orifices. These findings provide quantitative insight into the role of viscoelastic confinement on droplet dynamics, informing the design of microfluidic systems for biomedical and industrial applications.