Liquid Interfaces: Spontaneous Non-Linear Oscillations by Surfactant Transfer

Author(s):  
Nina M. Kovalchuk ◽  
Dieter Vollhardt ◽  
Reinhard Miller
2012 ◽  
Vol 10 (5) ◽  
pp. 1423-1441 ◽  
Author(s):  
Nina Kovalchuk

AbstractSystems far from equilibrium are able to self-organize and often demonstrate the formation of a large variety of dissipative structures. In systems with free liquid interfaces, self-organization is frequently associated with Marangoni instability. The development of solutal Marangoni instability can have specific features depending on the properties of adsorbed surfactant monolayer. Here we discuss a general approach to describe solutal Marangoni instability and review in details the recent experimental and theoretical results for a system where the specific properties of adsorbed layers are crucial for the observed dynamic regimes. In this system, Marangoni instability is a result of surfactant transfer from a small droplet located in the bulk of water to air/water interface. Various dynamic regimes, such as quasi-steady convection with a monotonous decrease of surface tension, spontaneous oscillations of surface tension, or their combination, are predicted by numerical simulations and observed experimentally. The particular dynamic regime and oscillation characteristics depend on the surfactant properties and the system aspect ratio.


2020 ◽  
Author(s):  
Milan Předota ◽  
Ondřej Kroutil ◽  
Denys Biriukov ◽  
Simone Pezzoti ◽  
Arianna Marchioro ◽  
...  

2015 ◽  
Vol 13 (1) ◽  
Author(s):  
Nina M. Kovalchuk

AbstractThree particular systems are considered where transfer of a surfactant across the interface between two immiscible liquids, water and oil, is accompanied by spontaneous oscillations of relaxation type with an abrupt decrease of interfacial tension followed by its gradual increase. These oscillations cannot be explained in the frameworks of linear stability analysis, because they are related to essentially non-linear effects. The oscillations characteristics depend on the properties of a surfactant (interfacial activity, solubility, partition coefficient, density difference between the surfactant solution and pure solvent), other solutes present in one or both liquid phases, and, usually, also on the system geometry. If the transferred surfactant is an ionic one, then, the oscillations of interfacial tension are synchronised with the oscillations of electric potential across the interface. The available hypothesis about oscillations mechanism are discussed, in particular, the model proposed recently for oscillations due to Marangoni instability by surfactant transfer from a point source located in one of the liquid bulk phases.


1967 ◽  
Vol 28 ◽  
pp. 105-176
Author(s):  
Robert F. Christy

(Ed. note: The custom in these Symposia has been to have a summary-introductory presentation which lasts about 1 to 1.5 hours, during which discussion from the floor is minor and usually directed at technical clarification. The remainder of the session is then devoted to discussion of the whole subject, oriented around the summary-introduction. The preceding session, I-A, at Nice, followed this pattern. Christy suggested that we might experiment in his presentation with a much more informal approach, allowing considerable discussion of the points raised in the summary-introduction during its presentation, with perhaps the entire morning spent in this way, reserving the afternoon session for discussion only. At Varenna, in the Fourth Symposium, several of the summaryintroductory papers presented from the astronomical viewpoint had been so full of concepts unfamiliar to a number of the aerodynamicists-physicists present, that a major part of the following discussion session had been devoted to simply clarifying concepts and then repeating a considerable amount of what had been summarized. So, always looking for alternatives which help to increase the understanding between the different disciplines by introducing clarification of concept as expeditiously as possible, we tried Christy's suggestion. Thus you will find the pattern of the following different from that in session I-A. I am much indebted to Christy for extensive collaboration in editing the resulting combined presentation and discussion. As always, however, I have taken upon myself the responsibility for the final editing, and so all shortcomings are on my head.)


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