Consistent temporal behaviors over a non-Newtonian/Newtonian two-phase flow

Abstract

The temporal behaviors of non-Newtonian/Newtonian two-phase flows are closely tied to flow pattern formation mechanisms, influenced significantly by the non-Newtonian index, and exhibiting nonlinear rheological characteristics. The rheological model parameters are model-dependent, resulting in poor predictability of their spatio-temporal characteristics. This limitation hinders the development of a unified analytical approach and consistent results, confining researches to case-by-case studies. In this study, sets of digital microfluidics experiments, along with continuous-discrete phase-interchanging schemes, yielded 72 datasets under various non-Newtonian fluid solution configurations, micro-channel structures, and multiple Carreau-related models. Among these datasets, we identified consistent temporal behaviors featuring non-Newtonian flow patterns in digital microfluidics. In the context of significant model dependency and widespread uncertainty in model parameters for non-Newtonian fluid characterization, this study demonstrates that the consistent representation of the non-Newtonian behavior exit, and may be essentially independent of specific data or models. Which finding holds positive implications for understanding the flow behavior and morphology of non-Newtonian fluids.