Dynamic responses of electrorheological fluid in steady pressure flow

Nam, Yoon Kwon; Park, M. K.; Yamane, Ryuichiro

doi:10.1007/s00348-007-0449-1

Cited by 15 publications

(20 citation statements)

References 23 publications

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“…Bingham flow in a channel 31,34,39,40 . The Bingham fluid model is commonly used to describe the macroscopic plastic behaviors of ER suspensions and it is useful for predicting the steady pressure drop of ER flows in a channel.…”

Section: Modelmentioning

confidence: 99%

“…Further experimental investigations to observe structure growth in ER fluids 33,34 have found that the rate of structure growth and the maximum size of the individual structures are determined by the competition between the field-induced particle interaction force and hydrodynamic forces. Similar dependencies were also observed in flowing magnetorheological fluids 35 .…”

Section: Introductionmentioning

confidence: 99%

“…However, a quantitative correlation between pressure drop and structure growth has not yet been achieved in these studies. In addition, although spatial variation in the microstructure was briefly mentioned in previous studies 33,34 , a systematic investigation of these variations and the resultant effect on the net pressure drop has not been performed.…”

Section: Introductionmentioning

confidence: 99%

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Structure evolution in electrorheological fluids flowing through microchannels

2013

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Enhanced knowledge of the transient behavior and characteristics of electrorheological (ER) fluids subject to time dependent electric fields carries the potential to advance the design of fast actuated hydraulic devices. In this study, the dynamic response of electrorheological fluid flows in rectilinear microchannels was investigated experimentally. Using high-speed microscopic imaging, the evolution of particle aggregates in ER fluids subjected to temporally stepwise electric fields was visualized. Nonuniform growth of the particle structures in the channel was observed and correlated to field strength and flow rate. Two competing time scales for structure growth were identified. Guided by experimental observations, we develop a phenomenological model to quantitatively describe and predict the evolution of microscale structures and the concomitant induced pressure gradient.

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Section: Modelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Structure evolution in electrorheological fluids flowing through microchannels

2013

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“…However, recent studies [12,15,16] indicate that there is a difference in the dynamic response of ER fluids in shear and flow modes. Lee and Choi [12] have compared the rheological properties of an ER fluid in both modes and observed that the Bingham yield stress is higher in flow mode.…”

Section: Introductionmentioning

confidence: 99%

“…Lee and Choi [12] have compared the rheological properties of an ER fluid in both modes and observed that the Bingham yield stress is higher in flow mode. Nam et al [15] have studied the dynamic response of an ER fluid in steady pressure-driven flow and found that the response in flow mode is dominated by a densification process in which the competition between particle interaction and hydrodynamic forces on the incoming particles leads to cluster formation. On the other hand, in shear mode, they note that the aggregation of chains into columns is the dominant process.…”

Section: Introductionmentioning

confidence: 99%

Yield Hardening of Electrorheological Fluids in Channel Flow

et al. 2016

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Electrorheological fluids offer potential for developing rapidly actuated hydraulic devices where shear forces or pressure-driven flow are present. In this study, the Bingham yield stress of electrorheological fluids with different particle volume fractions is investigated experimentally in wall-driven and pressuredriven flow modes using measurements in a parallel-plate rheometer and a microfluidic channel, respectively. A modified Krieger-Dougherty model can be used to describe the effects of the particle volume fraction on the yield stress and is in good agreement with the viscometric data. However, significant yield hardening in pressure-driven channel flow is observed and attributed to an increase and eventual saturation of the particle volume fraction in the channel. A phenomenological physical model linking the densification and consequent microstructure to the ratio of the particle aggregation time scale compared to the convective time scale is presented and used to predict the enhancement in yield stress in channel flow, enabling us to reconcile discrepancies in the literature between wall-driven and pressure-driven flows.

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