Experimental study on the relationship between extensional and shear rheology of low-viscosity power-law fluids

TL;DR

This study experimentally explores the correlation between extensional and shear rheology in low-viscosity power-law fluids, demonstrating conditions where their viscosities share the same power-law exponents.

Contribution

First experimental evidence linking extensional and shear viscosity exponents in low-viscosity power-law fluids using capillary breakup and shear rheometry.

Findings

Power-law relationship holds for extensional and shear viscosities at Oh > 1.

Extensional and shear viscosities measured over a wide range of viscosities.

Same power exponents observed for both viscosities under experimental conditions.

Abstract

This paper investigates the relationship between extensional and shear viscosity of low-viscosity power-law fluids. We show the first experimental evidence of the conditions satisfying the same power exponents for extensional and shear viscosity, as indicated by the Carreau model. The extensional and shear viscosity are respectively measured by capillary breakup extensional rheometry dripping-onto-substrate (CaBER-DoS) and by a shear rheometer for various Ohnesorge number Oh. The viscosity ranges measured are about O(10^0) to O(104) mPas for shear viscosity and O(10^1) to O(10^3) mPas for apparent extensional viscosity. Our experimental results show that, at least for the range of Oh > 1, the power-law expression for the liquid filament radius, apparent extensional viscosity, and shear viscosity holds, even for low-viscosity fluids under our experimental conditions.