Unstable flows of concentrated suspensions

Quemada, D.

doi:10.1007/3-540-11581-1_8

Cited by 31 publications

(6 citation statements)

References 25 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…We note that the oscillation cycle does not coincide with the hysteresis cycle of the pressure-flow rate curve [presented schematically in the inset of Fig. 7b], contrarily to what has been suggested by Quemada (1982) and Hatzikiriakos and Dealy (1992). In particular, the amplitudes of pressure and flow rate oscillations are somewhat lower than those, P hyst and Q hyst , imposed by the hysteresis.…”

Section: B Pressure/flow Rate Oscillationsmentioning

confidence: 55%

“…However, the macroscopic origin of the flow instabilities is essentially similar for most of the fluids. Pressure-driven flows become unstable in the range of the flow rates corresponding to a decreasing branch of the pressure-flow rate curve [Quemada (1982)], while simple shear flows exhibit instabilities at shear rates belonging to the decreasing branch of the stress versus shear rate curve (flow curve) [Yerushalmi et al (1970)]. In both situations, we deal with a negative differential viscosity of the fluid, which induces momentum transfer from the slower fluid layers to the faster ones.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Instabilities of a pressure-driven flow of magnetorheological fluids

Rodríguez‐Arco

Kuzhir

López–López

et al. 2013

Journal of Rheology

View full text Add to dashboard Cite

International audienceIn this work, we studied a pressure-driven flow of a magnetorheological suspension through a cylindrical tube in the presence of a non-uniform magnetic field perpendicular to the tube and varying along its axis. The flow was realized with the help of a commercial capillary rheometer in a controlled-velocity mode. Experimental pressure-flow rate curves exhibited a local minimum, and flow instabilities were observed in the range of flow rates corresponding to the decreasing branch of these curves. The non-monotonic behavior of the flow curves is attributed to the interplay between the hydrodynamic dissipation and the interaction between particle aggregates and walls. Our theoretical model, based on the particle flux conservation, correctly predicts the shape of the pressure-flow rate curves and indicates the speed range within which flow instabilities are expected. These instabilities are manifested by somewhat regular oscillations of the pressure difference and of the outlet flow rate at a constant imposed piston speed. Visualization of particle structures in a transparent tube revealed that the flow oscillations were governed by both the suspension compressibility and the stick-slip of the aggregates on the tube walls. This study is motivated by the problem of particle clogging in magnetorheological smart devices employing non-uniform magnetic fields

show abstract

Section: B Pressure/flow Rate Oscillationsmentioning

confidence: 55%

Section: Introductionmentioning

confidence: 99%

Instabilities of a pressure-driven flow of magnetorheological fluids

Rodríguez‐Arco

Kuzhir

López–López

et al. 2013

Journal of Rheology

View full text Add to dashboard Cite

show abstract

“…A very similar nonmonotonic stress-shear rate behavior was observed by Pignon et al (1996) for Brownian suspensions of laponite particles. This shape of the rheogram suggests unstable flows of the suspension, since it is well known that a steady state homogeneous flow with a linear velocity profile is absolutely unstable within the range of shear rates corresponding to the decreasing branch of the rheogram -see for instance Quemada (1982). Within this domain of negative differential viscosity, the shear rate may vary from point to point in the suspension, and, strictly speaking, we are not allowed to define the shear rate in the common way as the ratio of the upper plate speed v to the gap thickness h. Therefore, from now in this work the quantity v/h is referred to as the apparent or global shear rate.…”

Section: Experimental Observationsmentioning

confidence: 99%

Stick–slip instabilities in the shear flow of magnetorheological suspensions

López–López¹,

Kuzhir²,

Rodríguez‐Arco³

et al. 2013

Journal of Rheology

View full text Add to dashboard Cite

SynopsysThis work is devoted to the stick-slip instabilities that appear in the shear flow of highly concentrated suspensions of magnetic microparticles. The effect of the applied magnetic field strength was analyzed in details. With this aim, homogeneous suspensions of iron microparticles with concentration near the limit of maximum-packing fraction were prepared, and shear-flow measurements were performed in a controlled-rate mode using a rheometer provided with a rough parallel-plate geometry. For each given value of the shear rate, the time evolution of the shear stress was monitored for at least 20 min. Saw-tooth-like stress oscillations, typical of stick-slip instabilities, were obtained at low enough shear rate values.The measurements were restricted to small enough oscillations, at which the rheometer was still able to maintain the shear rate constant. From the microscopic viewpoint, these stick-slip instabilities principally appear due to the periodic failure and healing of the field-induced particle structures, as inferred from experimental observations. This hypothesis is corroborated by a theoretical model developed on the basis of the balance of the magnetic and hydrodynamic torques over the particle structures, allows us to predict the correct order of magnitude of the main parameters of the stick-slip instabilities, including the amplitude and period of the stress oscillations.

show abstract

“…4 was derived by Dougherty (1959) and Krieger (1972), except that the exponent was -[] ∅ . A yet simpler form, in which the exponent was given as -2, was reported by Maron and Pierce (1956) and Quemada (1982).…”

Section: Einstein's Theorymentioning

confidence: 99%

Rheology of nanocellulose-rich aqueous suspensions: A Review

Hubbe

Tayeb

Joyce

et al. 2017

BioRes

224

View full text Add to dashboard Cite

The flow characteristics of dilute aqueous suspensions of cellulose nanocrystals (CNC), nanofibrillated cellulose (NFC), and related products in dilute aqueous suspensions could be of great importance for many emerging applications. This review article considers publications dealing with the rheology of nanocellulose aqueous suspensions in the absence of matrix materials. In other words, the focus is on systems in which the cellulosic particles themselves – dependent on their morphology and the interactive forces between them – largely govern the observed rheological effects. Substantial progress in understanding rheological phenomena is evident in the large volume of recent publications dealing with such issues including the effects of flow history, stratification of solid and fluid layers during testing, entanglement of nanocellulose particles, and the variation of inter-particle forces by changing the pH or salt concentrations, among other factors. Better quantification of particle shape and particle-to-particle interactions may provide advances in future understanding. Despite the very complex morphology of highly fibrillated cellulosic nanomaterials, progress is being made in understanding their rheology, which supports their usage in applications such as coating, thickening, and 3D printing.

show abstract

Unstable flows of concentrated suspensions

Cited by 31 publications

References 25 publications

Instabilities of a pressure-driven flow of magnetorheological fluids

Instabilities of a pressure-driven flow of magnetorheological fluids

Stick–slip instabilities in the shear flow of magnetorheological suspensions

Rheology of nanocellulose-rich aqueous suspensions: A Review

Contact Info

Product

Resources

About