Drop profile analysis tensiometry under highly dynamic conditions

The results of measured surface tension by the use of drop profile analysis tensiometry (PAT) under dynamic conditions indicate acceptable values at low Reynolds numbers, however for high Reynolds numbers show surface tension values significantly lower than the physical expected values. [Display omi...

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Bibliographic Details
Published in:Colloids and surfaces. A, Physicochemical and engineering aspects Vol. 413; pp. 292 - 297
Main Authors: Karbaschi, M., Bastani, D., Javadi, A., Kovalchuk, V.I., Kovalchuk, N.M., Makievski, A.V., Bonaccurso, E., Miller, R.
Format: Journal Article
Language:English
Published: Elsevier B.V 05.11.2012
Subjects:
air
bubbles
Capillary pressure technique
colloids
Drop profile analysis
Dynamic surface tension measurements
Dynamic tests
Dynamical systems
Dynamics
equations
Fluid dynamics of growing drop
Gauss–Laplace equation
hexane
Hexanes
High speed
Liquids
Mathematical analysis
PAT
Fluid dynamics of growing drop
Drop profile analysis
Dynamic surface tension measurements
Capillary pressure technique
Gauss–Laplace equation
ISSN:0927-7757, 1873-4359
Online Access:Get full text
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Summary:The results of measured surface tension by the use of drop profile analysis tensiometry (PAT) under dynamic conditions indicate acceptable values at low Reynolds numbers, however for high Reynolds numbers show surface tension values significantly lower than the physical expected values. [Display omitted] ► Profile analysis tensiometry under dynamic conditions can be discriminated to three regions. ► Low Re number: deviations from Laplacian shape are small and the surface tension values are correct. ► Intermediate Re number: deviations from Laplacian shape are small but the surface tension values are significantly low. ► High Reynolds numbers: neither Std nor the obtained surface tension values are acceptable. Profile analysis tensiometry (PAT) is presently the most frequently used technique for measuring surface tensions of liquids. The basis of this methodology is however an equilibrium force balance as given by the Gauss–Laplace equation. Therefore, its application under dynamic conditions, i.e. for growing drops or bubbles, is questionable. We discuss the limits of the applicability of PAT under dynamic conditions by using a growing drop configuration equipped with a high speed video camera. The systems studied are the water/air and water/hexane interface. The obtained “dynamic” drop profiles are analyzed by fitting the classical Gauss–Laplace equation. The results are additionally compared with experimental data obtained from capillary pressure tensiometry. The analysis allows defining three different regions related to respective drop expansion rates.
Bibliography:http://dx.doi.org/10.1016/j.colsurfa.2012.04.027
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ISSN:0927-7757
1873-4359
DOI:10.1016/j.colsurfa.2012.04.027