Electrical conductivity of isotropic fibre suspensions

Sundararajakumar, R. R.; Koch, Donald L.

doi:10.1098/rspa.1999.0386

Cited by 5 publications

(1 citation statement)

References 10 publications

(11 reference statements)

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“…Nsom (1994) presented the results of a theoretical study of dilute and semi-concentrated suspensions of sti ÿbers, in which the drag reduction is directly computed with respect to the cylinder radii ratio, the ÿber concentration and density. In addition, it is reported that a minimum of highly conducting ÿbers enhances the thermal and electrical conductivity of composites (Mackaplow et al, 1994;Sundararajakumar and Koch, 1999).…”

Section: Introductionmentioning

confidence: 99%

Hydrodynamic instability of fiber suspensions in channel flows

You

Lin

2004

Fluid Dyn. Res.

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A linear stability analysis of channel ow in the presence of ÿber suspensions is performed. Based on slender-body theory, a modiÿed stability equation is derived by using the natural closure approximation to determine the ÿber orientation. It is found that the ow instability of ÿber suspensions is governed by two parameters: H , a ratio between the axial stretching resistance of ÿbers and the inertial force of the uid, and the orientational di usivity coe cient C I that accounts for inter-ÿber hydrodynamic interactions. The increment of either parameter causes an increase of critical Reynolds number, a reduction of the maximum disturbance growth rate and a shift of the peak value of velocity disturbances away from the walls. Hence, the ÿber additives e ectively attenuate the instability of the ow. The orientation distribution state of ÿbers in the ow is also examined, and the in uence of parameters is determined. An investigation of di erent terms in the vorticity disturbance equation and an enstrophy-based energy analysis reveal the sources of disturbance energy and the mechanisms behind the instability of ÿber suspensions. Finally, an experiment is performed using the visualization technique. The comparative measurements of stable lengths in every type of ow show that ÿber additives have a stabilizing e ect on the ow, and this e ect is clearer for higher values of Re. The conclusions of experiment are in agreement with those of linear instability analysis.

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Section: Introductionmentioning

confidence: 99%

Hydrodynamic instability of fiber suspensions in channel flows

You

Lin

2004

Fluid Dyn. Res.

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Evaluation of fiber orientation in plant fiber-cement composites using AC-impedance spectroscopy

Wansom

Janjaturaphan

2013

Cement and Concrete Research

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A multiscale approach to predict the effective conductivity of a suspension using the asymptotic homogenization method

2022

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This work aims to implement the asymptotic homogenization method (AHM) to predict the effective thermal/electrical conductivity for suspensions with aligned inclusions. Exploiting the substantial separation of length scales between the macroscopic and microscopic structures, multiscale modelling using AHM capitalizes on the perturbations of the potential field caused due to the presence of an inclusion under a macroscopic loading are used to predict the effective property. The analytical formulation for the thermal/electrical conductivity problem is derived, and subsequently, the finite element (FE) formulation required to solve the unit cell problem is described. The results obtained for a cylindrical inclusion are validated against known analytical solutions for both the dilute (Mori-Tanaka) and concentrated volume fractions (Φ) of the inclusion. The study revealed that Mori-Tanaka (MT) estimate and AHM agree well at Φ less than 0.4. However, near maximum packing fractions, AHM results fared significantly better than MT when compared with known asymptotic forms (J. Keller, Journal of Applied Physics, 34, 991, (1963)). The proposed AHM method is then implemented to structures with aligned spheroidal inclusions of various aspect ratios and conductivity ratios, thus providing a more generalized approach to predict the effective thermal/electrical conductivity. The results obtained are bench-marked and validated systematically against known analytical expressions.

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Electrical conductivity of isotropic fibre suspensions

Cited by 5 publications

References 10 publications

Hydrodynamic instability of fiber suspensions in channel flows

Hydrodynamic instability of fiber suspensions in channel flows

Evaluation of fiber orientation in plant fiber-cement composites using AC-impedance spectroscopy

A multiscale approach to predict the effective conductivity of a suspension using the asymptotic homogenization method

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