scholarly journals Padé approximant for normal stress differences in large-amplitude oscillatory shear flow

2018 ◽  
Vol 30 (4) ◽  
pp. 040910 ◽  
Author(s):  
P. Poungthong ◽  
C. Saengow ◽  
A. J. Giacomin ◽  
C. Kolitawong ◽  
D. Merger ◽  
...  
Keyword(s):  
Shear Flow ◽  
Normal Stress ◽  
Large Amplitude ◽  
Padé Approximant ◽  
Oscillatory Shear ◽  
Large Amplitude Oscillatory Shear ◽  
Pade Approximant ◽  
Oscillatory Shear Flow ◽  
Normal Stress Differences

Normal Stress Differences of Human Blood in Unidirectional Large-Amplitude Oscillatory Shear Flow

2020 ◽  
Vol 142 (12) ◽  
Author(s):  
Chaimongkol Saengow ◽  
Alan Jeffrey Giacomin ◽  
Andrea Stephanie Dimitrov
Keyword(s):  
Shear Flow ◽  
Normal Stress ◽  
Human Blood ◽  
Stress Responses ◽  
Large Amplitude ◽  
Normal Stress Difference ◽  
Stress Difference ◽  
Large Amplitude Oscillatory Shear ◽  
Oscillatory Shear Flow ◽  
Normal Stress Differences

Abstract This work analyzes normal stress difference responses in blood tested in unidirectional large-amplitude oscillatory shear flow (udLAOS), a novel rheological test, designed for human blood. udLAOS mimics the pulsatile flow in veins and arteries, in the sense that it never reverses, and yet also nearly stops once per heartbeat. As for our continuum fluid model, we choose the Oldroyd 8-constant framework for its rich diversity of popular constitutive equations, including the corotational Jeffreys fluid. This work arrives at exact solutions for normal stress differences from the corotational Jeffreys fluid in udLAOS. We discover fractional harmonics comprising the transient part of the normal stress difference responses, and both integer and fractional harmonics, the alternant part. By fractional, we mean that these occur at frequencies other than integer multiples of the superposed oscillation frequency. More generally, predictions from the Oldroyd 8-constant framework are explored by means of the finite difference method. Finally, the generalized versions of both the Oldroyd 8-constant framework and the corotational Jeffreys fluid are employed to predict the nonlinear normal stress responses for the model parameters fitted to udLAOS measurements from three very different donors, all healthy. From our predictions, we are led to expect less variation in normal stress differences in udLAOS from healthy donor to donor, than for the corresponding measured shear stress responses.

The first normal stress difference of non-Brownian hard-sphere suspensions in the oscillatory shear flow near the liquid and crystal coexistence region

Soft Matter ◽  
2020 ◽  
Vol 16 (43) ◽  
pp. 9864-9875
Author(s):  
Young Ki Lee ◽  
Kyu Hyun ◽  
Kyung Hyun Ahn
Keyword(s):  
Shear Flow ◽  
Normal Stress ◽  
Hard Sphere ◽  
Normal Stress Difference ◽  
Oscillatory Shear ◽  
Stress Difference ◽  
Large Amplitude Oscillatory Shear ◽  
First Normal Stress Difference ◽  
Oscillatory Shear Flow ◽  
Sphere Suspensions

The first normal stress difference (N1) as well as shear stress of non-Brownian hard-sphere suspensions in small to large amplitude oscillatory shear flow is investigated.

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