Universal features of the shape of elastic fibres in shear flow

Żuk, Paweł J.; Słowicka, Agnieszka M.; Ekiel-Jeżewska, Maria L.; Stone, Howard A.

doi:10.1017/jfm.2020.1048

Cited by 29 publications

(40 citation statements)

References 88 publications

(172 reference statements)

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“…In experiments and numerical simulations we observe that for most of the 3D initial orientations bending starts locally from the fiber ends, by analogy to previously reported experiments and numerical simulations of fibers initially aligned with the flow [27,29,41]. We first focus on our numerical simulations.…”

Section: Longer Timessupporting

confidence: 74%

“…We demonstrate that the compressional buckling happens only once, for time smaller than half of the Jeffery period, and for a very limited range of initial orientations. In section 6 we show that the most common bending pattern is different-bending originates locally at the fiber ends [41]. Finally, conclusions are presented in section 7.…”

Section: Introductionmentioning

confidence: 94%

“…In the numerical simulations, the 3D dynamics of a single fiber are evaluated, in contrast to the previous 2D analysis [41,46]. Here we focus on short-time transient effects rather than studying the long-time approach to attracting modes of the dynamics as in [41]. The fiber is initially straight and at elastic equilibrium.…”

Section: Initial Conditions and Early Timesmentioning

confidence: 99%

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Buckling of elastic fibers in a shear flow

et al. 2022

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Three-dimensional dynamics of flexible fibers in shear flow are studied numerically, with a qualitative comparison to experiments. Initially, the fibers are straight, with different orientations with respect to the flow. By changing the rotation speed of a shear rheometer, we change the ratio A of bending to shear forces. We observe fibers in the flow-vorticity plane, which gives insight into the motion out of the shear plane. The numerical simulations of moderately flexible fibers show that they rotate along effective Jeffery orbits, and therefore the fiber orientation rapidly becomes very close to the flow-vorticity plane, on average close to the flow direction, and the fiber remains in an almost straight configuration for a long time. This ``ordering'' of fibers is temporary since they alternately bend and straighten out while tumbling. We observe numerically and experimentally that if the fibers are initially in the compressional region of the shear flow, they can undergo a compressional buckling, with a pronounced deformation of shape along their whole length during a short time, which is in contrast to the typical local bending that originates over a long time from the fiber ends. We identify differences between local and compressional bending and discuss their competition, which depends on the initial orientation of the fiber and the bending stiffness ratio A. There are two main finding. First, the compressional buckling is limited to a certain small range of the initial orientations, excluding those from the flow-vorticity plane. Second, since fibers straighten out in the flow-vorticity plane while tumbling, the compressional buckling is transient - it does not appear for times longer than 1/4 of the Jeffery period. For larger times, bending of fibers is always driven by their ends.

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Section: Longer Timessupporting

confidence: 74%

Section: Introductionmentioning

confidence: 94%

Section: Initial Conditions and Early Timesmentioning

confidence: 99%

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Buckling of elastic fibers in a shear flow

et al. 2022

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“…The flow of a polymer solution has commonly appeared in synthetic and application processes for the manufacturing of various materials and fibers. This kind of flow is also commonly found in fluid control and other microfabricated sensing technologies [ 1 , 2 ]. Concerning the dynamics of polymer molecules under shear, they are known to be modeled by Kuhn’s bead-spring model, which deforms as a function of the shear rate and the angle of the molecule with respect to the shear direction when hydrodynamic force is applied [ 3 ].…”

Section: Introductionmentioning

confidence: 99%

“…These results were inconsistent with the classical assumption that polymer molecules are elongated when shear is applied [ 3 , 4 ]. Simulations focusing on a single polymer, which could be assumed as a limit of a dilute solution system, suggested that the buckling and stretching of polymer chains in solution were repeated under shear [ 1 , 7 ]. This result was also different from the classical assumption and was confirmed in experiments [ 8 , 9 ].…”

Section: Introductionmentioning

confidence: 99%

FRET Measurement of Polymer Response under Shear

Iwao

Yamaguchi

Obata

et al. 2021

Sensors

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Polymer solutions under shear flow are often observed in manufacturing processes. Classically, polymer behavior is represented by Kuhn’s bead-spring model, in which only the elongation of polymer chains is assumed. In recent years, the compression of polymer chains under shear flow has been reported. In this study, we investigated the behavior of polymer chains dissolved in various concentrations under shear flow. We measured the time variation of the fluorescence intensity emitted from a FRET (fluorescence resonance energy transfer) polymer, which enabled us to study the change in the distance between both ends of a polymer chain. The polymer chains appeared to stretch and compress depending on the concentration of the polymer solution. The results showed that the deformation of polymer chains was different from the classical theory. The FRET measurement is a promising diagnostic method for understanding the dynamics of polymer chains.

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