Non-Newtonian Behavior of an Insoluble Monolayer: Effects of Inertia

Lopez, Juan M.; Miraghaie, Reza; Hirsa, Amir

doi:10.1006/jcis.2001.8198

Cited by 15 publications

(13 citation statements)

References 18 publications

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“…This occurs at concentration values where the surface pressure, Π, increases dramatically (figure 8b), indicative of a second-order phase transition to a liquid solid as A decreases. A study of another insoluble monolayer, hemicyanine, showed similar non-Newtonian shear thinning behaviour (Lopez, Miraghaie & Hirsa 2002). Considering measurement uncertainties, including that of c 0 which for the present study is ± 6%, and the uncertainty in the state (phase) of the monolayer, which can depend on, amongst other factors, how it was spread, our measurements are consistent with those reported by Poskanzer & Goodrich (1975).…”

Section: Determination Of Surface Shear Viscositysupporting

confidence: 90%

Determination of surface shear viscosity via deep-channel flow with inertia

2002

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Results of an experimental and computational study of the flow in an annular region bounded by stationary inner and outer cylinders and driven by the rotation of the floor are presented. The top is a flat air/water interface, covered by an insoluble monolayer. We develop a technique to determine the surface shear viscosity from azimuthal velocity measurements at the interface which extends the range of surface shear viscosity that can be measured using a deep-channel viscometer in the usual Stokes flow regime by exploiting flow inertia. A Navier–Stokes-based model of bulk flow coupled to a Newtonian interface that has surface shear viscosity as the only interfacial property is developed. This is achieved by restricting the flow to regimes where the surface radial velocity vanishes. The use of inertia results in an improved signal-to-noise ratio of the azimuthal velocity measurements by an order of magnitude beyond that available in the Stokes flow limit. Measurements on vitamin K1 and stearic acid monolayers were performed, and their surface shear viscosities over a range of concentrations are determined and found to be in agreement with data in the literature.

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Section: Determination Of Surface Shear Viscositysupporting

confidence: 90%

Determination of surface shear viscosity via deep-channel flow with inertia

2002

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“…The Reynolds number considered here is small but finite, which means that it ranges between the Stokes limit (Re = 0) and the weakly inertial flow (Re ~ 100 typically). Beyond this limit, as already mentioned, flow topology is well documented by direct numerical studies carried out by Lopez and coworkers [ 16,17]. Furthermore, our approach will show how flow patterns evolve according to the vertical and horizontal aspect ratios, especially when the vertical aspect ratio is small (radially extended cavity).…”

Section: Introductionmentioning

confidence: 78%

“…Despite both its fundamental interest and its relevance in applications related to crystal growth [12] "laurent.davoust@simap.grenoble-inp.fr 7Current address: bioMerieux, Technology Research Dpt., Centre Christophe Merieux, 38024 Grenoble, France. or surface viscosimetry [13][14][15], it is surprising to see how end-driven annular flows have not attracted as much attention as full cylinders. Most existing studies on annular channel flows have been performed numerically or experimentally [13,[15][16][17], quite often with the aim of investigating the impact of physicochemical contamination along the upper liquid surface. To our knowledge, except for the recent analytical modeling performed by Shtern [18,19] for an annular cavity considered as semi-infinite along the vertical direction, all existing analytical studies devoted to this configuration only focus on the azimuthal flow either when the liquid surface is free of contamination [20] or when it is contaminated [21,22],…”

Section: Introductionmentioning

confidence: 99%

Low-to-moderate Reynolds number swirling flow in an annular channel with a rotating end wall

2015

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This paper presents a new method for solving analytically the axisymmetric swirling flow generated in a finite annular channel from a rotating end wall, with no-slip boundary conditions along stationary side walls and a slip condition along the free surface opposite the rotating floor. In this case, the end-driven swirling flow can be described from the coupling between an azimuthal shear flow and a two-dimensional meridional flow driven by the centrifugal force along the rotating floor. A regular asymptotic expansion based on a small but finite Reynolds number is used to calculate centrifugation-induced first-order correction to the azimuthal Stokes flow obtained as the solution at leading order. For solving the first-order problem, the use of an integral boundary condition for the vorticity is found to be a convenient way to attribute boundary conditions in excess for the stream function to the vorticity. The annular geometry is characterized by both vertical and horizontal aspect ratios, whose respective influences on flow patterns are investigated. The vertical aspect ratio is found to involve nontrivial changes in flow patterns essentially due to the role of corner eddies located on the left and right sides of the rotating floor. The present analytical method can be ultimately extended to cylindrical geometries, irrespective of the surface opposite the rotating floor: a wall or a free surface. It can also serve as an analytical tool for monitoring confined rotating flows in applications related to surface viscosimetry or crystal growth from the melt.

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“…At low flow rates, the governing factor is the surface shear viscosity; high rates of bottom rotation give rise to secondary flows. Therefore, the monolayer, which is first uniformly distributed over the surface, moves toward the inner cylinder [179][180][181]. The quantitative theory of this method based on the numerical solution of Scriven's equation (28) was developed in works cited above.…”

Section: Other Methodsmentioning

confidence: 99%

Methods of measuring rheological properties of interfacial layers (Experimental methods of 2D rheology)

2009

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-Current methods of studying the rheological properties of interfacial layers at the interfaces of fluids are reviewed. This area of research includes two-dimensional 2D rheology. Regardless of the similarities between the parameters of rheological properties of two-dimensional and bulk (three-dimensional) systems, when measuring surface properties, it is necessary to reformulate the main experimental methods to allow for the different dimensions of surface and bulk characteristics of material. Parameters of shear and dilational (measured upon expansion-compression) properties of interfacial layers are distinguished, and the latter are considered to be independent parameters of a system. The most attention was given to the rotational methods of measuring shear viscosity and the components of the complex 2D elastic modulus, as well as to measuring surface tension upon harmonic changes of the bubble (droplet) surface area, which allows characteristics of the dilational behavior of thin liquid films to be determined. Both groups of methods are widely used in laboratory practice and realized in the form of a number of original and commercial instruments. Dilational measurements of interfacial layers can also be performed with oscillations of a movable barrier on a Langmuir trough. In addition, methods based on the propagation of capillary waves across the surface of a liquid, as well as rarer methods of capillary flow in thin channels forced by either a surface tension gradient or the motion of the interface, are considered.

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Non-Newtonian Behavior of an Insoluble Monolayer: Effects of Inertia

Cited by 15 publications

References 18 publications

Determination of surface shear viscosity via deep-channel flow with inertia

Determination of surface shear viscosity via deep-channel flow with inertia

Low-to-moderate Reynolds number swirling flow in an annular channel with a rotating end wall

Methods of measuring rheological properties of interfacial layers (Experimental methods of 2D rheology)

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