Coagulation efficiency of colloidal particles in shear flow

Vanni, Marco; Baldi, Giancarlo

doi:10.1016/s0001-8686(01)00050-1

Cited by 60 publications

(59 citation statements)

References 31 publications

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“…Furthermore, since the growth (A b , A s ) and breakage (B s ) rates are not equal the relaxation rate is asymmetric around the steady state even at the same shear rate: The time scale depends on whether the φ is increasing or decreasing. With these properties, the model follows first-principles colloidal models, in which the kernels are usually asymmetric and shear dependent [9,27,28], and complies with what is found experimenally as well [29][30][31][32][33]. Finally, the Maxwell stress element in the viscoelastic model introduces another time scale through stress evolution, which can be tuned using G 0 .…”

Section: Modelmentioning

confidence: 67%

“…In the model, the structure dynamics is proportional toγ −k , a known fact in some of the first-principles collision models for colloids [9,27,28] and also experimentally observed in numerous complex fluids [29][30][31][32][33]. Since the fluid structure dynamically relaxes at a rate imposed by the current shear rate, but the waiting time t w in the experimental protocol is fixed, below a certain shear rate, the structure fails to recover the steady state.…”

Section: Discussionmentioning

confidence: 96%

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Dynamic hysteresis in the rheology of complex fluids

Puisto

Mohtaschemi²,

Alava³

et al. 2015

Phys. Rev. E

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Recently, rheological hysteresis has been studied systematically in a wide range of complex fluids combining global rheology and time-resolved velocimetry. In this paper we present an analysis of the roles of the three most fundamental mechanisms in simple-yield-stress fluids: structure dynamics, viscoelastic response, and spatial flow heterogeneities, i.e., time-dependent shear bands. Dynamical hysteresis simulations are done analogously to rheological ramp-up and -down experiments on a coupled model which incorporates viscoelasticity and time-dependent structure evolution. Based on experimental data, a coupling between hysteresis measured from the local velocity profiles and that measured from the global flow curve has been suggested. According to the present model, even if transient shear banding appears during the shear ramps, in typical narrow-gap devices, only a small part of the hysteretic response can be attributed to heterogeneous flow. This results in decoupling of the hysteresis measured from the local velocity profiles and the global flow curve, demonstrating that for an arbitrary time-dependent rheological response this proposed coupling can be very weak.

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Section: Modelmentioning

confidence: 67%

Section: Discussionmentioning

confidence: 96%

Dynamic hysteresis in the rheology of complex fluids

Puisto

Mohtaschemi²,

Alava³

et al. 2015

Phys. Rev. E

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“…For bulk shear flow, the capture efficiency has been determined both experimentally and theoretically, for example, for systems with repulsive electrostatic interactions and attractive van der Waals attraction. 38,39 To estimate the effect of geometrical confinement on the capture cross section, a simplified profile of the attraction force is assumed, in which the attraction is zero when the gap between the particle surfaces is larger than a certain critical value and becomes dominant with respect to the hydrodynamic lubrication force when the gap between the particles becomes smaller than the critical value. This critical value is system-dependent, and for the purpose of illustrating the qualitative effect, a value ϵ g,crit = 2 × 10 −3 is assumed.…”

Section: B a Simplified Characterization Of Aggregate Formationmentioning

confidence: 99%

Lubrication analysis of interacting rigid cylindrical particles in confined shear flow

Cardinaels

Stone

2015

Physics of Fluids

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Lubrication analysis is used to determine analytical expressions for the elements of the resistance matrix describing the interaction of two rigid cylindrical particles in two-dimensional shear flow in a symmetrically confined channel geometry. The developed model is valid for non-Brownian particles in a low-Reynolds-number flow between two sliding plates with thin gaps between the two particles and also between the particles and the walls. Using this analytical model, a comprehensive overview of the dynamics of interacting cylindrical particles in shear flow is presented. With only hydrodynamic interactions, rigid particles undergo a reversible interaction with no cross-streamline migration, irrespective of the confinement value. However, the interaction time of the particle pair substantially increases with confinement, and at the same time, the minimum distance between the particle surfaces during the interaction substantially decreases with confinement. By combining our purely hydrodynamic model with a simple on/off non-hydrodynamic attractive particle interaction force, the effects of confinement on particle aggregation are qualitatively mapped out in an aggregation diagram. The latter shows that the range of initial relative particle positions for which aggregation occurs is increased substantially due to geometrical confinement. The interacting particle pair exhibits tangential and normal lubrication forces on the sliding plates, which will contribute to the rheology of confined suspensions in shear flow. Due to the combined effects of the confining walls and the particle interaction, the particle velocities and resulting forces both tangential and perpendicular to the walls exhibit a non-monotonic evolution as a function of the orientation angle of the particle pair. However, by incorporating appropriate scalings of the forces, velocities, and doublet orientation angle with the minimum free fraction of the gap height and the plate speed, master curves for the forces versus orientation angle can be constructed.

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“…However, the clusters could break up under large shear stresses, at high shear, and the aggregation rate levels off or even decreases. Several experiments investigating these phenomena qualitatively confirmed such expectations (Mousa et al 2001;Vanni and Baldi 2002). The difficulty in conducting aggregation experiments, based on van der Waals interactions, lies in the sensitivity of the attractive forces to variations on the particle surfaces and in the solution.…”

Section: Introductionmentioning

confidence: 53%

Cluster formation and growth in microchannel flow of dilute particle suspensions

Gudipaty

Stamm

Cheung

et al. 2010

Microfluid Nanofluid

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The lifetime of microfluidic devices depends on their ability to maintain flow without interruption. Certain applications require microdevices for transport of liquids containing particles. However, microchannels are susceptible to blockage by solid particles. Therefore, in this study, the phenomenon of interest is the formation and growth of clusters on a microchannel surface in the flow of a dilute suspension of hard spheres. Based on the present experiments, aggregation of clusters was observed for particleladen flows in microchannels with particle void fraction as low as 0.001 and particle diameter to channel height ratio as low as 0.1. The incipience and growth of a single cluster is discussed, and the spatial distribution and time evolution of clusters along the microchannel are presented. Although the cluster size seems to be independent of location, more clusters are found at the inlet/outlet regions than in the microchannel center. Similarly as for an individual cluster, as long as particle-cluster interaction is the dominant mode, the total cluster area in the microchannel grows almost linearly in time. The effects of flow rate, particle size, and concentration are also reported.

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Coagulation efficiency of colloidal particles in shear flow

Cited by 60 publications

References 31 publications

Dynamic hysteresis in the rheology of complex fluids

Dynamic hysteresis in the rheology of complex fluids

Lubrication analysis of interacting rigid cylindrical particles in confined shear flow

Cluster formation and growth in microchannel flow of dilute particle suspensions

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