SURFACTANT TRANSPORT INTO THE DROP UNDER CONDITIONS OF WEAK GRAVITATIONAL CONVECTION

Paper number

IAC-12,A2,4,4,x16284

Author

Prof. Antonio Viviani*, Seconda Universita' di Napoli, Italy

Coauthor

Dr. M. O. Denisova, Institute of Continuous Media Mechanics, UB Russian Academy of Sciences, Russia

Coauthor

Dr. K.G. Kostarev, Institute of Continuous Media Mechanics, UB Russian Academy of Sciences, Russia

Coauthor

Dr. A. V. Shmyrov, Institute of Continuous Media Mechanics, UB Russian Academy of Sciences, Russia

Coauthor

Prof. Andrew Zuev, Institute of Continuous Media Mechanics, UB Russian Academy of Sciences, Russia

Year

2012

Abstract

The paper presents the results of experimental study of mass transfer between the drop of
initially homogeneous insoluble fluid and aqueous solution of a surface-active agent
(surfactant). The research has been carried out in the framework of terrestrial modeling of the
space experiment "Diffusion of a surfactant into a drop" scheduled for implementation on
board the spacecraft Foton-M4 in autumn 2013. In the laboratory experiments a
chlorobenzene drop, having the form of a short cylinder with flat ends and free lateral surface,
was placed in a thin horizontal liquid layer filling a Hele-Shaw cell, which allowed us to
maximally suppress the effect of the gravitational convection and thus to model the
microgravity conditions. The flow structures and surfactant concentration fields inside and
outside the drop during its saturation by the surfactant (isopropyl alcohol) were visualized
using the interferometric technique. The research shows that under the terrestrial conditions
even at a weak gravitational convection the penetration of the surfactant into the drop is a
rather complicated process specified by the initial surfactant concentration in the solution and
by the degree of the solution inhomogeneity. Diffusion of the surfactant into the drop gives
rise to local concentration and surface tension variations along the drop interface, which
results in the development of a large-scale three-dimensional convective motion of
gravitational and solutocapillary nature inside and around the drop. When the initial surfactant
concentration С0 of the solution exceeds 30% the capillary flow displaces the gravitational
one and becomes a dominant flow pattern both in the drop and in the layer. At С0 = 50% the
phase boundary between the drop and the solution disappears due to an increase in the mutual
solubility of the basic fluids. As a result a three-component liquid mixture is formed.
The work was supported by Russian Academy of Sciences program № 12-Т-1-1008,
Russian Foundation for Basic Research project №. 10-01-96028 and grant for International
Research Teams of Ministry of Education and Science of Perm Region № С-26/210.

Abstract document

IAC-12,A2,4,4,x16284.brief.pdf

Manuscript document

IAC-12,A2,4,4,x16284.pdf (🔒 authorized access only).

To get the manuscript, please contact IAF Secretariat.