Hydrodynamic response of a surfactant-laden interface to a radial flow

Abstract

We study the features of a radial Stokes flow due to a submerged jet directed toward a liquid-air interface. The presence of surface-active impurities confers to the interface an in-plane elasticity that resists the incident flow. Both analytical and numerical calculations show that a minute amount of surfactants is enough to profoundly alter the morphology of the flow. The hydrodynamic response of the interface is affected as well, shifting from slip to no-slip boundary condition as the surface compressibility decreases. We argue that the competition between the divergent outward flow and the elastic response of the interface may actually be used as a practical way to detect and quantify a small amount of impurities. arXiv:1909.13540v1 [cond-mat.soft]

Motion of micro- and nano- particles interacting with a fluid interface

“…In the case of a particle straddling an interface the key parameter for the particle drag is the particle contact angle which determine the partition between the two fluids with different viscosities [6]. Hydrodynamics can also be used to treat the situation when surface active species are present at the interface; a relatively high surface concentration of such species confers specific surface viscosities to the interface and changes the flow boundary conditions (BC) [7] [8]. Even tiny quantity of such species may dramatically affect the BC as recently predicted [9].…”

“…The interfacial flow resulting from the combined effect of a Marangoni stress and the particle motion has been addressed more in detailed by Bickel et al [7]. In this work, a limiting radius on the interface is defined.…”

“…The value of the delimiting radius is highly sensitive to the surface species concentration, and thus to the surface tension. As suggested by the author, the measurement of the delimiting radius can therefore in principle be used to obtain the surface tension with a resolution improved of orders of magnitude compared to standard techniques [7].…”

Mechanisms of formation vortex structures at the liquid-gas interface with an adsorption layer

“…Численный эксперимент позволит внести ясность в природу неустойчивости однородного течения в области, занятой плёнкой ПАВ. Однако в большинстве моделей закладывается сохранение исходной (осевой) симметрии, в связи с чем при решении задачи течение также оказывается осесимметричным [1].…”

Stokes Equation in a Semi-Infinite Region: Generalization of the Lamb Solution and Applications to Marangoni Flows

“…The first reason for that comes from the presence of the interface itself, which breaks the symmetry in the direction perpendicular to it. The second reason lies in the fact that Marangoni flows are usually coupled to transport phenomena, leading to intricate relations even in the linear regime [8,9]. It was also suggested in recent experimental studies that the presence of surface-active impurities at the interface might induce hydrodynamic instabilities at vanishing Reynolds numbers [10,11].…”