Wall slip and viscous dissipation in sheared foams: Effect of surface mobility

Denkov, Nikolai D.; Subramanian, Vivek; Gurovich, Daniel; Lips, Alex

doi:10.1016/j.colsurfa.2005.02.038

Cited by 183 publications

(353 citation statements)

References 43 publications

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“…The surfactant Tween-20 (polyoxyethylene (20) sorbitan monolaurate) is non-ionic and has a molecular weight of 1228 g mol 21 and a CMC of 0.059 mM. The second surfactant we used, SDS, is anionic, and has a molecular weight of 288 g mol 21 and a CMC of 8.2 mM.…”

Section: The Experimental Designmentioning

confidence: 99%

The pressure drop along rectangular microchannels containing bubbles

et al. 2007

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This paper derives the difference in pressure between the beginning and the end of a rectangular microchannel through which a flowing liquid (water, with or without surfactant, and mixtures of water and glycerol) carries bubbles that contact all four walls of the channel. It uses an indirect method to derive the pressure in the channel. The pressure drop depends predominantly on the number of bubbles in the channel at both low and high concentrations of surfactant. At intermediate concentrations of surfactant, if the channel contains bubbles (of the same or different lengths), the total, aggregated length of the bubbles in the channel is the dominant contributor to the pressure drop. The difference between these two cases stems from increased flow of liquid through the ''gutters''-the regions of the system bounded by the curved body of the bubble and the corners of the channel-in the presence of intermediate concentrations of surfactant. This paper presents a systematic and quantitative investigation of the influence of surfactants on the flow of fluids in microchannels containing bubbles. It derives the contributions to the overall pressure drop from three regions of the channel: (i) the slugs of liquid between the bubbles (and separated from the bubbles), in which liquid flows as though no bubbles were present; (ii) the gutters along the corners of the microchannels; and (iii) the curved caps at the ends of the bubble.

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Section: The Experimental Designmentioning

confidence: 99%

The pressure drop along rectangular microchannels containing bubbles

et al. 2007

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“…For realistic surfactants, one expects the mobility of the interface to be at least somewhat impaired, so that dissipation in the thin film regions between bubbles and plate (figure 5b) becomes important. Indeed, Denkov et al (2005) showed theoretically and experimentally that, in the opposite limit of rigid interfaces, viscous resistance scales as Ca 1/2 .…”

Section: Foam Dynamics: a First-principle Study In Rheologymentioning

confidence: 99%

“…in rheometers. Denkov et al (2005) have measured the shear stress of wet foam (ez10%) with small bubble size (Lw30 mm) in a parallel-plate rheometer. By contrast, we use a pressure-driven flow set-up, namely a HeleShaw cell (Hele-Shaw 1898), and reproduce the quasi-two-dimensional set-up theoretically introduced by Bretherton (1961), whose experimental results were for tubes, not parallel plates.…”

Section: (A ) Hele-shaw Flowsmentioning

confidence: 99%

Foam: a multiphase system with many facets

Hilgenfeldt

Arif

Tsai

2008

Phil. Trans. R. Soc. A.

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Liquid foams are an extreme case of multiphase flow systems: capable of flow despite a very high dispersed phase volume fraction, yet exhibiting many characteristics of not only viscoelastic materials but also elastic solids. The non-trivial, well-defined geometry of foam bubbles is at the heart of a plethora of dynamical processes on widely varying length and time scales. We highlight recent developments in foam drainage (liquid dynamics) and foam rheology (flow of the entire gas-liquid system), emphasizing that many poorly understood features of other materials have precisely defined and quantifiable analogues in aqueous foams, where the only ingredients are well-known material parameters of Newtonian fluids and bubble geometry, together with subtle but important information on the surface mobility of the foam. Not only does this make foams an ideal model system for the theorist, but also an exciting object for experimental studies, in which dynamical processes span length scales from nanometres (thin films) to metres (foam continuum flows) and time scales from microseconds (film rupture) to minutes (foam rheology).

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“…[33][34][35][36][37][38] It has been shown that the friction coefficient depends on the capillary number (ratio of viscous forces to surface tension forces) but varies with the nature of the foam. For threedimensional foams, two sources of dissipation need to be taken into account.…”

Section: Introductionmentioning

confidence: 99%

“…The second contribution depends on the interfacial rheology of the foam and is induced by the presence of surfactant molecules at air/liquid interfaces. 33,37 To characterize the relative magnitude of the different contributions, a distinction should be made between low and high surface moduli. At high surface modulus, interfaces behave as incompressible surfaces.…”

Section: Introductionmentioning

confidence: 99%

Damping of liquid sloshing by foams

et al. 2015

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When a container is set in motion, the free surface of the liquid starts to oscillate or slosh. Such effects can be observed when a glass of water is handled carelessly and the fluid sloshes or even spills over the rims of the container. However, beer does not slosh as readily as water, which suggests that foam could be used to damp sloshing. In this work, we study experimentally the effect on sloshing of a liquid foam placed on top of a liquid bath. We generate a monodisperse two-dimensional liquid foam in a rectangular container and track the motion of the foam. The influence of the foam on the sloshing dynamics is experimentally characterized: only a few layers of bubbles are sufficient to significantly damp the oscillations. We rationalize our experimental findings with a model that describes the foam contribution to the damping coefficient through viscous dissipation on the walls of the container. Then we extend our study to confined three-dimensional liquid foam and observe that the behavior of 2D and confined 3D systems are very similar. Thus we conclude that only the bubbles close to the walls have a significant impact on the dissipation of energy. The possibility to damp liquid sloshing using foam is promising in numerous industrial applications such as the transport of liquefied gas in tankers or for propellants in rocket engines.

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Wall slip and viscous dissipation in sheared foams: Effect of surface mobility

Cited by 183 publications

References 43 publications

The pressure drop along rectangular microchannels containing bubbles

The pressure drop along rectangular microchannels containing bubbles

Foam: a multiphase system with many facets

Damping of liquid sloshing by foams

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