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Extracting extensional properties through excess pressure drop estimation in axisymmetric contraction and expansion flows for constant shear viscosity, extension strain-hardening fluids

Magda Nyström (Institutionen för material- och tillverkningsteknik, Polymera material och kompositer) ; H. R. T. Jahromi ; Mats Stading (Institutionen för material- och tillverkningsteknik, Polymera material och kompositer) ; M. F. Webster
Rheologica Acta (0035-4511). Vol. 55 (2016), 5, p. 373-396.
[Artikel, refereegranskad vetenskaplig]

In this study, hyperbolic contraction-expansion flow (HCF) devices have been investigated with the specific aim of devising new experimental measuring systems for extensional rheological properties. To this end, a hyperbolic contraction-expansion configuration has been designed to minimize the influence of shear in the flow. Experiments have been conducted using well-characterized model fluids, alongside simulations using a viscoelastic White-Metzner/FENE-CR model and finite element/finite volume analysis. Here, the application of appropriate rheological models to reproduce quantitative pressure drop predictions for constant shear viscosity fluids has been investigated, in order to extract the relevant extensional properties for the various test fluids in question. Accordingly, experimental evaluation of the hyperbolic contraction-expansion configuration has shown rising corrected pressure drops with increasing elastic behaviour (D e=0 similar to 16), evidence which has been corroborated through numerical prediction. Moreover, theoretical to predicted solution correspondence has been established between extensional viscosity and first normal stress difference. This leads to a practical means to measure extensional viscosity for elastic fluids, obtained through the derived pressure drop data in these HCF devices.

Nyckelord: Hyperbolic contraction, Pressure drop, Viscoelastic fluid, Boger fluid, Extensional flow, Axisymmetric contraction-expansion



Denna post skapades 2016-06-17. Senast ändrad 2016-06-22.
CPL Pubid: 237854

 

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Institutioner (Chalmers)

Institutionen för material- och tillverkningsteknik, Polymera material och kompositer

Ämnesområden

Teknisk mekanik

Chalmers infrastruktur