Dynamics Behavior of Droplet in Hydrophilic Contraction Microchannel

The droplet-based microfluidics technology achieves precise control over the behavior of droplets by designing the microchannel, controlling the flow, and managing the interactions of incompatible liquids. In this study, three-dimensional ( 3D ) numerical simulations were conducted to investigate the behavior of droplets in a hydrophilic microchannel. With a hydrophilic microchannel, both wetting characteristics and microchannel geometric play a significant role in influencing the motion and behavior of droplets. The research introduces various droplet behavior regimes influenced by the contact angle ( θ ), capillary number ( Ca ), and viscosity ratio ( λ ), demonstrating that the influence of the hydrophilic microchannel occurs only at low capillary numbers. A predictive model for the critical capillary number to transition between contact and non-contact behaviors with the microchannel surface is proposed, described as follows: \(Ca>f\left(\lambda \right)({a}_{1}C+{a}_{2})\). This research provides valuable insights for liquid-phase system analysis devices that can analyze and manipulate fluids in a hydrophilic microchannel.