Rheology of dilute suspensions of charged fibers
作者:
Shing Bor Chen,
Donald L. Koch,
期刊:
Physics of Fluids
(AIP Available online 1996)
卷期:
Volume 8,
issue 11
页码: 2792-2807
ISSN:1070-6631
年代: 1996
DOI:10.1063/1.869085
出版商: AIP
数据来源: AIP
摘要:
The rheology of a dilute suspension of charged fibers with a large ratio of lengthLto diameterdis examined. The fibers may possess both a net charge and a charge dipole and it is assumed that the Hartmann number is small. The double layer thickness &lgr; is large compared with the rod diameter and may be comparable with the fiber length. Although the shear rate is sufficiently small so that the deformation of the double layer is small, no restriction is placed on the rotary Pe´clet number of the rods. The velocity disturbance caused by the rods is neglected when calculating the double layer deformation. This approximation is accurate when &lgr;/L=O(1) andL/dis very large, but leads to an overestimate of the ion cloud distortion for small values of &lgr;/Lor moderate values ofL/d. The counterion cloud affects the stress both directly through a primary electroviscous stress and indirectly by exerting an electric torque that changes the fiber orientation distribution. The additional stress caused by electrostatics shear thins for a fiber with a net charge. However, when the fiber has a charge dipole, the electrical stress may increase with increasing shear rate at sufficiently high Pe´clet numbers. At very high Pe´clet numbers, the electrical torque can lead to a fixed orientation of the fibers near the flow direction of the simple shear flow. ©1996 American Institute of Physics.
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