Flow analysis for wormlike micellar solutions in an axisymmetric capillary channel

Yamamoto, Takehiro; Hashimoto, Takamasa; Yamashita, Astushi

doi:10.1007/s00397-008-0302-3

Cited by 2 publications

(4 citation statements)

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“…More specifically, they observed undulations along the interface in the gradient/neutral plane. Similar behaviour was observed in pipe Poiseuille flow of a wormlike micellar solution [42].…”

Section: Introductionsupporting

confidence: 76%

“…However, as reported in the literature, shear-banded fluids are susceptible to the development of elastic instabilities, and thus, it is of great interest to predict the flow conditions for which the flow of these fluids become highly unstable in order to avoid incorrect measurements of rheological data and in order to predict difficulties in industrial flows. These flow instabilities driven by elasticity have been observed in micellar solutions in different geometries, such as Taylor-Couette rheometers [15,34,27], cone-and-plate [6], microchannel [35,25,21] and pipe flows [42], to name a few.…”

Section: Introductionmentioning

confidence: 99%

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Bulk and interfacial modes of instability in channel flow of thixotropic-viscoelasto-plastic fluids with shear-banding

Castillo

Wilson

2020

Journal of Non-Newtonian Fluid Mechanics

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We carry out a linear stability analysis of the generalised BMP model, which incorporates the shear-banding phenomenon into flows of thixotropicviscoelasto-plastic fluids: common behaviours observed in wormlike micellar solutions. We introduce a new dimensionless parameter governing shear-banding, and find that when a flow is unstable in the absence of shear-banding, this parameter has a stabilising effect. Above a critical value of the shear-banding parameter, shear bands appear in the flow gradient direction. Here two different modes of instability are observed: a bulk mode (which is the same as that seen in the absence of shear banding) and an interfacial mode. We found that the former dominates over the latter at low values of the shear-banding parameter, but the interfacial instability becomes dominant at very high values of the parameter. In particular, the interfacial modes are more unstable in flows where the low shear band has almost constant viscosity. The two modes of instability depend on different material timescales: interfacial modes become more dangerous if the interface location is near the channel wall, which is seen when the structural relaxation time is much larger than that of plasticity, while bulk modes (as seen in previous work) are highly unstable if the timescale of viscoelasticity is much longer than both those of plasticity and thixotropy.

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Section: Introductionsupporting

confidence: 76%

Section: Introductionmentioning

confidence: 99%

Bulk and interfacial modes of instability in channel flow of thixotropic-viscoelasto-plastic fluids with shear-banding

Castillo

Wilson

2020

Journal of Non-Newtonian Fluid Mechanics

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“…Boek et al [38] have modified the Oldroyd-B Bautista model, since extensional viscosity predictions of the original Bautista model showed instability at large extensional flow rate values. Such model is later known as the MBM model and was used by later researchers to describe flow of micellar solutions in a circular axisymmetric capillary channel [39,40]. In this work, we will use the original Bautista et al model since the flow type developing inside the droplet that we will investigate in this work is predominantly shearing type.…”

Section: Modeling Shear Thinning Behavior Of Droplet Phasementioning

confidence: 99%

“…σ * αβ is the stress value of the droplet phase, Go is the elastic modulus, τ B is the relaxation time of the Bautista model, and k is a structural relaxation parameter of the droplet phase. The latter parameter is taken to be a constant in this work, although other publications have assumed that k is dependent on flow strength [39]. The symbol ∇ placed on top of the stress tensor denotes the upper convected derivative.…”

Section: Modeling Shear Thinning Behavior Of Droplet Phasementioning

confidence: 99%

Modeling the Deformation of Shear Thinning Droplets Suspended in a Newtonian Fluid

2020

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In this work, we carried out numerical modeling of the large deformation of a shear thinning droplet suspended in a Newtonian matrix using the constrained volume model. The adopted approach was to consider making incremental corrections to the evolution of the droplet anisotropy equation in order to capture the experimental behavior of a shear thinning droplet when subjected to deformation due to imposed flow. The constrained volume model was modified by using different models to describe the viscosity of droplet phase: the Bautista et al. model, the Carreau-Yasuda model and the Power-law model. We found that by combining the constrained volume model with a simple shear thinning viscosity model we were able to describe the available experimental data for large deformation of a shear thinning droplet suspended in a Newtonian matrix. Moreover, we developed an equation approximating flow strength during droplet retraction, and we found that the model can accurately describe the experimental data of the retraction of a shear thinning droplet.

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Flow analysis for wormlike micellar solutions in an axisymmetric capillary channel

Cited by 2 publications

References 0 publications

Bulk and interfacial modes of instability in channel flow of thixotropic-viscoelasto-plastic fluids with shear-banding

Bulk and interfacial modes of instability in channel flow of thixotropic-viscoelasto-plastic fluids with shear-banding

Modeling the Deformation of Shear Thinning Droplets Suspended in a Newtonian Fluid

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