Numerical Study on Polymer Non-Newtonian Droplet Impingement

The impact of droplets on surfaces is widely applied in inkjet printing and additive manufacturing. Industrial fluids often exhibit non-Newtonian properties (e.g., shear-thinning or viscoelasticity) due to additives. While existing studies focus on Newtonian fluids, this work investigates non-Newtonian droplet dynamics using a numerical model combining the volume of fluid (VOF) and level set methods to track phase interfaces. The effects of polymer concentration on the droplet impact behavior are analyzed. The results show that increase in the polymer concentration enhances viscous dissipation during impact, leading to significant morphological changes. Specifically, the higher concentrations reduce the maximum dimensionless spreading diameter, increase the maximum dimensionless height, delay the splashing onset, elevate secondary droplet positions, and amplify lateral deviation from the centerline. Upon impacting the high-temperature surfaces, the surface heat flux of polymer droplets initially increases and then decreases due to field synergy effects. These findings establish predictive correlations for controlling droplet deposition in oil–water separation applications, emphasizing the critical role of rheological tailoring in optimizing impact outcomes.