Comparative Analysis of Non-Newtonian Effects on Temporal and Spatial Characteristics of Droplet Generation: Non-Newtonian Fluid as Dispersed or Continuous Phase in Coaxial Two-Phase Flow

TL;DR

This study compares how non-Newtonian and Newtonian fluids affect droplet formation in coaxial flow, revealing unique phase diagrams and a rare synchronous transition phenomenon unaffected by phase interchange.

Contribution

It introduces phase diagrams based on the Carreau model with negative non-Newtonian index and uncovers a synchronous transition phenomenon in droplet generation.

Findings

Negative non-Newtonian index phase diagrams ('butterfly' and 'grape') are reported for the first time.

Symmetry observed in flow behavior at specific flow rate ratios and non-Newtonian index values.

Interchanging phases does not alter droplet characteristics during the synchronous transition.

Abstract

Comparative Analysis on temporal and spatial behaviors of droplets produced in a converging co-flow has been investigated when interchanging of phases, NaAlg (non-Newtonian) and soybean oil (Newtonian). The Carreau model is promoted and gave rarely reported negative non-Newtonian index, $n<0$, by which phase diagrams of "butterfly distribution" on temporal $f \cdot \tau \sim\left(Q_d / Q_c\right)^n$ space and "grape distribution" on spatial $d^* / D_c \sim\left(Q_d / Q_c\right)^n$ space are distinguished for the first time. These flow charts shows symmetry on refined expression $\left(Q_d / Q_c\right)^n=1$, (either $Q_d / Q_c=1$ or $n=0$) for both comparative experiments. We also find an interesting synchronous transition phenomenon exist, where the interchanging of disperse and continuous phases will not affect their temporal and spatial characteristics of drop generating, which is dynamically rarely happened.