Integrated photoelasticity measurements of a three-dimensional laminar flow: second-order stress terms in the stress-optic law

Nakamine, K.; Yokoyama, Yasuhisa; Worby, William; Muto, Masakazu; Tagawa, Yoshiyuki

doi:10.1364/opticaopen.21967049.v1

Cited by 3 publications

(3 citation statements)

References 41 publications

(79 reference statements)

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“…These experimental findings have also been verified by numerical calculations, which established that the regions in which the impact of 3D effects are found to be dominant are close to the plane of symmetry 16 . This phenomenon has been reported in circular and rectangular channels with aspect ratios close to 1 [17][18][19] . It has been concluded that this is due to shear on the upper and lower surfaces of the channel, although quantitative insights were limited.…”

Section: Introductionsupporting

confidence: 69%

Examination of flow birefringence induced by the shear components along the optical axis using a parallel-plate-type rheometer

Worby,

Nakamine,

Yokoyama

et al. 2024

Preprint

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In this study, the concept of rheo-optics is applied that explores the flow birefringence caused by stress components along the optical axis of the camera since it is often overlooked in the traditional theories of photoelastic flow measurement. A novel aspect of this research is that it involved conducting polarization measurements on simple shear flows, specifically from a perspective in which a shear-velocity gradient exists along the camera's optical axis. A parallel-plate-type rheometer and a polarization camera are employed for these systematic measurements. The experimental findings for dilute aqueous cellulose nanocrystal suspensions demonstrates that the flow birefringence can be expressed as a power law based on the power of the second invariant of the deformation-rate tensor. This suggests that flow birefringence can be universally characterized by the coordinate-independent invariants and a pre-factor determined by the direction of polarization measurement. By adjusting the nonlinear term in the stress-optic law, its applicability could be expanded to include three-dimensional fluid stress fields in which the stress is distributed along the camera's optical axis.

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Section: Introductionsupporting

confidence: 69%

Examination of flow birefringence induced by the shear components along the optical axis using a parallel-plate-type rheometer

Worby,

Nakamine,

Yokoyama

et al. 2024

Preprint

View full text Add to dashboard Cite

show abstract

“…Fitting was also conducted in different cases, and it was verified that the magnitude of C 2 was O(10 −7 -10 −6 ). Note that C 1 values for fluids have been reported to be O(10 −7 -10 −5 ) in previous studies (Ito et al 2016;Nakamine et al 2023). Although their units are different and therefore need to be discussed, C 1 and C 2 were found to be of similar magnitudes.…”

Section: Resultsmentioning

confidence: 67%

“…This can be explained as being due to the shear caused by the upper and lower surfaces of the channel wall. This discrepancy between theory and experiment is more significant in the case of three-dimensional flows, where the contribution of the shear components along the optical axis is larger (Kim et al 2017;Nakamine et al 2023).…”

mentioning

confidence: 90%

Measurement of flow birefringence induced by the shear components along the optical axis using a parallel-plate-type rheometer

Worby,

Nakamine,

Yokoyama

et al. 2023

Preprint

Self Cite

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The present study investigated the flow birefringence induced by shear components along a camera's optical axis, which has been neglected in conventional theories of photoelastic measurements. Measurements were conducted for a wide range of shear rates from a direction perpendicular to the shear using a high-speed polarization camera and a parallel-plate-type rheometer. The measurement results obtained from a fluid with low viscoelasticity, specifically a dilute suspension of cellulose nanocrystals, showed that the birefringence increases monotonically as the stress components along the camera's optical axis increase. It was also found that the birefringence showed a power law with respect to the shear rate. This letter reports a key fact required for polarization measurements of shear rate (shear stress) in three-dimensional flows.

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Two-dimensional strain rate imaging study using a polarization camera and birefringent aqueous cellulose nanocrystal suspensions

Lane,

Baumann,

Rode

et al. 2023

Exp Fluids

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The birefringence response of aqueous cellulose nanocrystal (CNC) suspensions in a two-dimensional laminar flow is measured and studied. The suspensions have CNC concentrations of 1.0 wt% (weight percentage) and 1.2 wt%. Cellulose nanocrystals are optically anisotropic rod-like particles that align when subjected to local velocity gradients, whereas at rest, they remain randomly orientated by Brownian motion. The alignment causes birefringence, a phenomenon also known as flow-induced birefringence. We study the flow through an additively manufactured flow channel and measure the amount of birefringence as well as the position of the refractive index axes by using polarizers and a polarization camera. With the help of reference data published in a previous study (Lane, Rode, et al., 2022a), strain rates are derived from the birefringence measurements and compared with numerical simulations. Two flow situations are studied, a plane Poiseuille flow and the flow around a cosine-shaped constriction. The experimentally derived shear rates for the plane Poiseuille flow are consistent with theoretical and computational results. The derived strain rates for the flow around the cosine-shaped constriction show an unexpected asymmetric profile, with the strain rates in the contraction zone being larger than in the expansion zone. The averaged orientation of the CNCs in the flow is linked to the position of the refractive index axes. In the contraction zone, the CNCs tend to align parallel to the flow, whereas in the expansion zone, the CNCs tend to align perpendicular to the flow. The results of this study are discussed in the context of previous, similar studies. The asymmetric strain rate profile around the cosine-shaped constriction is thought to originate from history effects, and the alignment of the CNCs is influenced by extensional rates.

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Integrated photoelasticity measurements of a three-dimensional laminar flow: second-order stress terms in the stress-optic law

Cited by 3 publications

References 41 publications

Examination of flow birefringence induced by the shear components along the optical axis using a parallel-plate-type rheometer

Examination of flow birefringence induced by the shear components along the optical axis using a parallel-plate-type rheometer

Measurement of flow birefringence induced by the shear components along the optical axis using a parallel-plate-type rheometer

Two-dimensional strain rate imaging study using a polarization camera and birefringent aqueous cellulose nanocrystal suspensions

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