Off-Equilibrium Surface Tension in Colloidal Suspensions

Truzzolillo, Domenico; Mora, Serge; Dupas, Christelle; Cipelletti, Luca

doi:10.1103/physrevlett.112.128303

Cited by 29 publications

(73 citation statements)

References 37 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Before recasting this expression in a way that is more suitable to analyze the experiments, two remarks are in order. First, although equation (7) has been derived in the limit n >> 1, we have shown [25] that, for realistic choices of the fluid and geometrical parameters, equation (7) represents an excellent approximation to the full solution already for n A 2. Thus, in the next section we will identify the number of fingers observed in experiments with n A as calculated from equation (7).…”

Section: Viscous Fingering: Overview Of Theorymentioning

confidence: 99%

“…Thus, the fastest-growing mode at any given time does not coincide in general with the mode that has developed the maximum amplitude. In recent theoretical and experimental studies [25,47] it has been proposed that the number of fingers observed at a given time is well approximated by the order of the mode with maximum amplitude at that time. In the following, we provide numerical evidence to support this assumption and calculate an asymptotic expression for the maximum-amplitude mode from which the interface tension may be obtained.…”

Section: Viscous Fingering: Overview Of Theorymentioning

confidence: 99%

“…These stresses will eventually decay at large enough time, because the suspension and the solvent are fully miscible, so that diffusion-driven mixing will finally erase any sharp interface. However, on short enough time scales, these stresses act as an effective interfacial tension, as it was already pointed out for the general case of miscible fluids with composition gradients more than 100 years ago, by mathematician and physicist D. Korteweg. In [25] we have shown that the effective surface tension of microgel suspensions can be rationalized in the framework of Korteweg's theory for miscible fluids. Here, we present new data on the effective surface tension between suspensions of hard, compact silica particles and their own solvent.…”

Section: Introductionmentioning

confidence: 99%

“…For example, recent work has shown that the addition of colloidal particles at the interface between two (immiscible) fluids may modify profoundly the mechanical properties of the interface, by imparting it mechanical rigidity as in "bijels" [20,21] or in non-spherical "armoured" bubbles [22,23], or by protecting bubbles and drops from coalescence [24]. Recently, we have explored the role of interfacial stresses in colloidal systems in what is arguably the most minimalist experimental configuration: the sharp interface between a colloidal suspension and its own solvent [25]. By investigating the onset of the Saffman-Taylor instability, a hydrodynamic instability ruled by the competition between viscosity and surface tension, in suspensions of PNiPAM microgels exposed to their solvent, we have shown that interfacial stresses develop at the suspension-solvent interface.…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Bulk and interfacial stresses in suspensions of soft and hard colloids

Truzzolillo

Roger

Dupas

et al. 2015

J. Phys.: Condens. Matter

View full text Add to dashboard Cite

Abstract.We explore the influence of particle softness and internal structure on both the bulk and interfacial rheological properties of colloidal suspensions. We probe bulk stresses by conventional rheology, by measuring the flow curves, shear stress vs strain rate, for suspensions of soft, deformable microgel particles and suspensions of near hard-sphere-like silica particles. A similar behavior is seen for both kind of particles in suspensions at concentrations up to the random close packing volume fraction, in agreement with recent theoretical predictions for sub-micron colloids. Transient interfacial stresses are measured by analyzing the patterns formed by the interface between the suspensions and their own solvent, due to a generalized Saffman-Taylor hydrodynamic instability. At odd with the bulk behavior, we find that microgels and hard particle suspensions exhibit vastly different interfacial stress properties. We propose that this surprising behavior results mainly from the difference in particle internal structure (polymeric network for microgels vs compact solid for the silica particles), rather than softness alone.

show abstract

Section: Viscous Fingering: Overview Of Theorymentioning

confidence: 99%

Section: Viscous Fingering: Overview Of Theorymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Bulk and interfacial stresses in suspensions of soft and hard colloids

Truzzolillo

Roger

Dupas

et al. 2015

J. Phys.: Condens. Matter

View full text Add to dashboard Cite

show abstract

“…While diffusion is disregarded in their analysis, here we identify molecular diffusion as the mechanism responsible for the shutdown of the instability at late times. In our experiments, the long-enough times (or small-enough strain rates) imply that diffusion plays a major role in the evolution of the interface, and that Korteweg stresses and nonequilibrium surface tension effects do not [56,[58][59][60][61][62][63][64][65][66]. As the unstable front grows in fingerlike structures [ Figs.…”

mentioning

confidence: 99%

Interface evolution during radial miscible viscous fingering

2015

View full text Add to dashboard Cite

We study experimentally the miscible radial displacement of a more viscous fluid by a less viscous one in a horizontal Hele-Shaw cell. For the range of tested injection rates and viscosity ratios we observe two regimes for the evolution of the fluid-fluid interface. At early times the interface length increases linearly with time, which is typical of the Saffman-Taylor instability for this radial configuration. However, as time increases, the interface growth slows down and scales as ∼t 1 2 , as one expects in a stable displacement, indicating that the overall flow instability has shut down. Surprisingly, the crossover time between these two regimes decreases with increasing injection rate. We propose a theoretical model that is consistent with our experimental results, explains the origin of this second regime, and predicts the scaling of the crossover time with injection rate and the mobility ratio. The key determinant of the observed scalings is the competition between advection and diffusion time scales at the displacement front, suggesting that our analysis can be applied to other interfacial-evolution problems such as the Rayleigh-Bénard-Darcy instability. A large number of natural and industrial flow processes depend on both the degree and the rate of mixing between fluids, such as chemical reactions [1][2][3][4], combustion [5], microbial activity [6], and enhanced oil recovery [7]. In such mixing-driven systems, the flow responsible for fluid displacement reflects the heterogeneity of the host medium structure [8][9][10][11] or the physical properties of the fluids, such as density [3,12,13] or viscosity [14,15]. Mixing takes place at the fluid-fluid interface and is determined by the combined action of molecular diffusion, which acts to reduce the local concentration gradients, and advection, which controls the interface dynamics [16][17][18][19][20][21]. Understanding the interface dynamics between two miscible fluids is therefore crucial to explaining and predicting the rate of mixing.When a less viscous fluid displaces a more viscous one, their interface is deformed and stretched by a hydrodynamical instability known as viscous fingering [15,22,23], and this results in complex interface dynamics [16,17,24]. Much work has focused on characterizing miscible viscous fingering, including laboratory experiments [25][26][27], numerical simulations [28][29][30][31][32], and linear stability analyses to model the onset and growth of instabilities for rectilinear [33] and radial [34,35] geometries. Other studies have also focused on the effects of anisotropic dispersion [31,33,36] [50], and flow configuration [51-55] on the viscous fingering instability. Despite the extensive work done, the effect of viscous fingering on mixing has only recently been investigated numerically for a rectilinear geometry [14,56]. While the dynamics of the interface between two miscible fluids is crucial to explain and predict the rate of mixing [1,16], a solid understanding of the temporal evolution of the viscously unstable fl...

show abstract

Nonlinear simulations of miscible viscous fingering with gradient stresses in porous media

Pramanik

Mishra

2015

Chemical Engineering Science

View full text Add to dashboard Cite

Off-Equilibrium Surface Tension in Colloidal Suspensions

Cited by 29 publications

References 37 publications

Bulk and interfacial stresses in suspensions of soft and hard colloids

Bulk and interfacial stresses in suspensions of soft and hard colloids

Interface evolution during radial miscible viscous fingering

Nonlinear simulations of miscible viscous fingering with gradient stresses in porous media

Contact Info

Product

Resources

About