Effects of surfactants on the motion and deformation of a droplet in thermocapillary migration

Ali Nadim, Ali Borhan

Research output: Contribution to journalConference article

13 Citations (Scopus)

Abstract

We examine the effects of surfactants on the terminal velocity and the shape of a droplet translating in an unbounded, otherwise quiescent liquid, under the influence of an externally imposed constant temperature gradient. It is assumed that the droplet surface tension depends much more weakly on the surfactant concentration than on the temperature. In such a circumstance and assuming no bulk transport, the surface concentration of the surfactant can be found exactly for all Peclet numbers, confirming the intuitively expected result that the surfactant tends to accumulate near the low temperature side of the droplet. This, in turn, partially lowers the surface tension on that side, thereby decreasing the terminal migration velocity of the droplet as a whole. At the same time, to first order in capillary number, the droplet assumes a prolate spheroidal shape.

Original languageEnglish (US)
Pages (from-to)753-764
Number of pages12
JournalPCH. Physicochemical hydrodynamics
Volume11
Issue number5-6
StatePublished - Dec 1 1989
Event7th International Physicochemical Hydrodynamics Conference - Cambridge, MA, USA
Duration: Jun 1 1989Jun 1 1989

Fingerprint

thermocapillary migration
Surface-Active Agents
Surface active agents
surfactants
interfacial tension
Surface tension
terminal velocity
Peclet number
translating
Phosmet
temperature gradients
Thermal gradients
liquids
Temperature
Liquids

All Science Journal Classification (ASJC) codes

  • Engineering(all)

Cite this

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abstract = "We examine the effects of surfactants on the terminal velocity and the shape of a droplet translating in an unbounded, otherwise quiescent liquid, under the influence of an externally imposed constant temperature gradient. It is assumed that the droplet surface tension depends much more weakly on the surfactant concentration than on the temperature. In such a circumstance and assuming no bulk transport, the surface concentration of the surfactant can be found exactly for all Peclet numbers, confirming the intuitively expected result that the surfactant tends to accumulate near the low temperature side of the droplet. This, in turn, partially lowers the surface tension on that side, thereby decreasing the terminal migration velocity of the droplet as a whole. At the same time, to first order in capillary number, the droplet assumes a prolate spheroidal shape.",
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Effects of surfactants on the motion and deformation of a droplet in thermocapillary migration. / Nadim, Ali; Borhan, Ali.

In: PCH. Physicochemical hydrodynamics, Vol. 11, No. 5-6, 01.12.1989, p. 753-764.

Research output: Contribution to journalConference article

TY - JOUR

T1 - Effects of surfactants on the motion and deformation of a droplet in thermocapillary migration

AU - Nadim, Ali

AU - Borhan, Ali

PY - 1989/12/1

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N2 - We examine the effects of surfactants on the terminal velocity and the shape of a droplet translating in an unbounded, otherwise quiescent liquid, under the influence of an externally imposed constant temperature gradient. It is assumed that the droplet surface tension depends much more weakly on the surfactant concentration than on the temperature. In such a circumstance and assuming no bulk transport, the surface concentration of the surfactant can be found exactly for all Peclet numbers, confirming the intuitively expected result that the surfactant tends to accumulate near the low temperature side of the droplet. This, in turn, partially lowers the surface tension on that side, thereby decreasing the terminal migration velocity of the droplet as a whole. At the same time, to first order in capillary number, the droplet assumes a prolate spheroidal shape.

AB - We examine the effects of surfactants on the terminal velocity and the shape of a droplet translating in an unbounded, otherwise quiescent liquid, under the influence of an externally imposed constant temperature gradient. It is assumed that the droplet surface tension depends much more weakly on the surfactant concentration than on the temperature. In such a circumstance and assuming no bulk transport, the surface concentration of the surfactant can be found exactly for all Peclet numbers, confirming the intuitively expected result that the surfactant tends to accumulate near the low temperature side of the droplet. This, in turn, partially lowers the surface tension on that side, thereby decreasing the terminal migration velocity of the droplet as a whole. At the same time, to first order in capillary number, the droplet assumes a prolate spheroidal shape.

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