Modeling tensorial conductivity of particle suspension networks

Olsen, Tyler; Kamrin, Kenneth N

doi:10.1039/c5sm00093a

Cited by 7 publications

(6 citation statements)

References 21 publications

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“…To do so, we characterize the microstructure of the gel network through the fabric tensor Z [42][43][44]. As two interacting particles approach within the attraction range, they form particle bonds.…”

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confidence: 99%

“…We seek to understand how evolution of the material on the microscale gives rise to these observed kinematic inhomogeneities. To do so, we characterize the microstructure of the gel network through the fabric tensor, Z [36][37][38]. As two interacting particles approach within the attraction range, they form particle bonds.…”

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confidence: 99%

“…As two interacting particles approach within the attraction range, they form particle bonds. To monitor the collective dynamics of the system we define, Z, from the local fabric [36][37][38] of single particles (…”

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Microstructural Rearrangements and their Rheological Implications in a Model Thixotropic Elastoviscoplastic Fluid

2017

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We identify the sequence of microstructural changes that characterize the evolution of an attractive particulate gel under flow and discuss their implications on macroscopic rheology. Dissipative particle dynamics is used to monitor shear-driven evolution of a fabric tensor constructed from the ensemble spatial configuration of individual attractive constituents within the gel. By decomposing this tensor into isotropic and nonisotropic components we show that the average coordination number correlates directly with the flow curve of the shear stress versus shear rate, consistent with theoretical predictions for attractive systems. We show that the evolution in nonisotropic local particle rearrangements are primarily responsible for stress overshoots (strain-hardening) at the inception of steady shear flow and also lead, at larger times and longer scales, to microstructural localization phenomena such as shear banding flow-induced structure formation in the vorticity direction. DOI: 10.1103/PhysRevLett.118.048003 Thixotropic elastoviscoplastic (TEVP) materials are a broad class of structured fluids that include (but are not limited to) most colloidal gels [1], nano emulsions [2], crude oils [3,4], and many biological systems such as blood clots and actin networks [5,6]. As a result of their complex underlying microstructure, TEVPs exhibit a wide range of rich and complex thermo-mechanical properties: Below a critical stress, the microstructural network formed by individual particles remains intact and resists large deformations by external forces. At this stage the macroscopic response of the material is similar to that of a viscoelastic solid. By progressively increasing the applied load, the material reaches its "yield stress" and starts to flow [7]. At this point the particle network that is responsible for solidlike response of the macroscopic sample undergoes plastic rearrangements over an increasingly wide range of length scales [8]. Upon complete yielding of this network, plastic flow results ultimately in a viscouslike response; however, as a result of constant formation and breakage events, the particle-level microstructure continues to evolve giving rise to thixotropic behavior. The many-body nature of the problem means that local forces exerted on a single particle change its energy landscape, which consequently defines its subsequent association or dissociation rate to neighboring particles [9,10]. When combined with multibody hydrodynamic effects in these fluids [11], the resulting microstructure-flow relationship becomes complex and may show long time scale transient behavior and multiple steady states [1,12]. This leads to a wide range of timedependent responses that can also be observed, including microphase separation [13], vorticity aligned structure formation [14][15][16], local rigid plug formation and shear banding [17], plus shear-induced rejuvenation of the particle network [18].Although the general form of the flow curve (relating the shear stress to shear rate) and some transient pheno...

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Microstructural Rearrangements and their Rheological Implications in a Model Thixotropic Elastoviscoplastic Fluid

2017

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“…To further characterize the microstructure of a suspension, we employ the fabric tensor concept, which was originally introduced for the contact network of granular materials. 48,49 The fabric tensor A p can be computed at the particle level using the following expression, 31,50,51 where N b is the number of the particles in contact, n i is the unit vector connecting the center of a particle to the center of its i th bond neighbors, and ⊗ denotes the dyadic product. The system-sized fabric tensor A can be then derived by averaging the particle-level fabric tensors over the particle ensemble,…”

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Multiscale nature of electric-field-induced structural formations in non-colloidal suspensions

Mirfendereski

Park

2022

Soft Matter

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“…In a previous numerical study [33], we modeled the conductivity tensor of a particle network as a function of the average fabric tensor A, by assuming the network could be represented by a regular lattice of identical particles with the same average fabric tensor. The fabric-lattice relationship can be inverted to obtain a model for conductivity as shown below in 3D:…”

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Coupled dynamics of flow, microstructure, and conductivity in sheared suspensions

et al. 2016

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We propose a model for the evolution of the conductivity tensor for a flowing suspension of electrically conductive particles. We use discrete particle numerical simulations together with a continuum physical framework to construct an evolution law for the suspension microstructure during flow. This model is then coupled with a relationship between the microstructure and the electrical conductivity tensor. Certain parameters of the joint model are fit experimentally using rheo-electrical conductivity measurements of carbon black suspensions under flow over a range of shear rates. The model is applied to the case of steady shearing as well as time-varying conductivity of unsteady flow experiments. We find that the model prediction agrees closely with the measured experimental data in all cases.

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Modeling tensorial conductivity of particle suspension networks

Cited by 7 publications

References 21 publications

Microstructural Rearrangements and their Rheological Implications in a Model Thixotropic Elastoviscoplastic Fluid

Microstructural Rearrangements and their Rheological Implications in a Model Thixotropic Elastoviscoplastic Fluid

Multiscale nature of electric-field-induced structural formations in non-colloidal suspensions

Coupled dynamics of flow, microstructure, and conductivity in sheared suspensions

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