scholarly journals Flow in a containerless liquid system: Ring-sheared drop with finite surface shear viscosity

2019 ◽  
Vol 4 (4) ◽  
Author(s):  
Shreyash Gulati ◽  
Frank P. Riley ◽  
Amir H. Hirsa ◽  
Juan M. Lopez
Keyword(s):  
Shear Viscosity ◽  
Liquid System ◽  
Surface Shear ◽  
Surface Shear Viscosity

scholarly journals Surface shear inviscidity of soluble surfactants

2014 ◽  
Vol 111 (10) ◽  
pp. 3677-3682 ◽  
Author(s):  
Zachary A. Zell ◽  
Arash Nowbahar ◽  
Vincent Mansard ◽  
L. Gary Leal ◽  
Suraj S. Deshmukh ◽  
...  
Keyword(s):  
Shear Viscosity ◽  
Nonionic Surfactants ◽  
Emulsion Stability ◽  
Foam Stability ◽  
Sensitivity Limit ◽  
Multiple Control ◽  
Surface Shear ◽  
Soluble Surfactants ◽  
Almost All ◽  
Surface Shear Viscosity

Foam and emulsion stability has long been believed to correlate with the surface shear viscosity of the surfactant used to stabilize them. Many subtleties arise in interpreting surface shear viscosity measurements, however, and correlations do not necessarily indicate causation. Using a sensitive technique designed to excite purely surface shear deformations, we make the most sensitive and precise measurements to date of the surface shear viscosity of a variety of soluble surfactants, focusing on SDS in particular. Our measurements reveal the surface shear viscosity of SDS to be below the sensitivity limit of our technique, giving an upper bound of order 0.01 μN·s/m. This conflicts directly with almost all previous studies, which reported values up to 103–104 times higher. Multiple control and complementary measurements confirm this result, including direct visualization of monolayer deformation, for SDS and a wide variety of soluble polymeric, ionic, and nonionic surfactants of high- and low-foaming character. No soluble, small-molecule surfactant was found to have a measurable surface shear viscosity, which seriously undermines most support for any correlation between foam stability and surface shear rheology of soluble surfactants.

The effect of surface shear viscosity on the damping of oscillations in millimetric liquid bridges

2011 ◽  
Vol 23 (8) ◽  
pp. 082102 ◽  
Author(s):  
Miguel A. Herrada ◽  
José M. Montanero ◽  
José M. Vega
Keyword(s):  
Shear Viscosity ◽  
Liquid Bridges ◽  
Surface Shear ◽  
Effect Of Surface ◽  
Surface Shear Viscosity

Impact of surface viscosity on the stability of a droplet translating through a stagnant fluid

2021 ◽  
Vol 927 ◽  
Author(s):  
Natasha Singh ◽  
Vivek Narsimhan
Keyword(s):  
Shear Viscosity ◽  
Capillary Number ◽  
Cavity Growth ◽  
Boundary Integral ◽  
Constitutive Relationship ◽  
Surface Viscosity ◽  
Surface Shear ◽  
The Stability ◽  
The Impact ◽  
Surface Shear Viscosity

This study examines the impact of interfacial viscosity on the stability of an initially deformed droplet translating through an unbounded quiescent fluid. The boundary-integral formulation is employed to investigate the time evolution of a droplet in the Stokes flow limit. The droplet interface is modelled using the Boussinesq–Scriven constitutive relationship having surface shear viscosity $\eta _\mu$ and surface dilatational viscosity $\eta _\kappa$ . We observe that, below a critical value of the capillary number, $Ca_C$ , the initially perturbed droplet reverts to its spherical shape. Above $Ca_C$ , the translating droplet deforms continuously, growing a tail at the rear end for initial prolate perturbations and a cavity for initial oblate perturbations. We find that surface shear viscosity inhibits the tail/cavity growth at the droplet's rear end and increases the $Ca_C$ compared with a clean droplet. In contrast, surface dilatational viscosity increases tail/cavity growth and lowers $Ca_C$ compared with a clean droplet. Surprisingly, both shear and dilatational surface viscosity appear to delay the time at which pinch off occurs, and hence satellite droplets form. Lastly, we explore the combined influence of surface viscosity and surfactant transport on droplet stability by assuming a linear dependence of surface tension on surfactant concentration and exponential dependence of interfacial viscosities on the surface pressure. We find that pressure-thinning/thickening effects significantly affect the droplet dynamics for surface shear viscosity but play a small role for surface dilatational viscosity. We lastly provide phase diagrams for the critical capillary number for different values of the droplet's viscosity ratio and initial Taylor deformation parameter.

Surface shear viscosity of Gibbs and Langmuir monolayers

1999 ◽  
Vol 397 ◽  
pp. 331-349 ◽  
Author(s):  
CATHERINE BARENTIN ◽  
CHRISTOPHE YBERT ◽  
JEAN-MARC DI MEGLIO ◽  
JEAN-FRANÇOIS JOANNY
Keyword(s):  
Shear Viscosity ◽  
Sodium Dodecyl ◽  
Langmuir Monolayers ◽  
Two Dimensional ◽  
Hydrodynamic Models ◽  
Surface Shear ◽  
Hydrodynamic Calculations ◽  
Good Agreement ◽  
Surface Shear Viscosity

In this paper, we present a new two-dimensional viscometer, and the hydrodynamic calculations used to obtain the surface viscosities from the measurements. In order to interpret the experiments, performed with solutions of sodium dodecyl sulfate (SDS) and also with monolayers of insoluble surfactants, we develop various hydrodynamic models of soluble Gibbs monolayers and of incompressible Langmuir monolayers, that describe well the experimental results. In the case of SDS solutions, the calculations allow the determination of the surface shear viscosity, and its value is in good agreement with previous studies.

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