Effect of surfactant on the dynamics of a crude oil droplet in water column: Experimental and numerical investigation

Abhijit Rao; Rupesh K. Reddy; Franz Ehrenhauser; Krishnaswamy Nandakumar; Louis J. Thibodeaux; Dandina Rao; Kalliat T. Valsaraj

doi:10.1002/cjce.22074

Effect of surfactant on the dynamics of a crude oil droplet in water column: Experimental and numerical investigation

Abhijit Rao, Rupesh K. Reddy, Franz Ehrenhauser, Krishnaswamy Nandakumar^*, Louis J. Thibodeaux, Dandina Rao, Kalliat T. Valsaraj

^*Corresponding author for this work

Research output: Contribution to journal › Article › peer-review

7 Scopus citations

Abstract

In this study we have investigated the effect of surfactant, sodium dodecyl sulfate (SDS), on the dynamics of a single crude oil droplet, rising in a quiescent water column. Experiments were conducted in a tank, in which an oil droplet was released into a stagnant water column through a nozzle. The droplets ranging from 0.3 to 0.85cm were produced from three different sized nozzles. The shape adopted by the emanating droplets varied from spherical to oblate. SDS concentrations were varied from 0 to 750ppm in water. The adsorption of surfactant reduced the interfacial tension at oil-water interface which resulted in generation of smaller sized droplets at the nozzle and caused the droplet to flatten. Consequently, the rise velocities of droplets decreased. A numerical model based on finite volume method was developed using commercial CFD package ANSYS Fluent®. The model employed volume of fluid method, suggested by Hirt and Nichols (Journal of Computational Physics 1981, 39, 201), with an interface reconstruction technique based on piecewise linear representation for tracking the oil-water interface. The influence of surface tension on the droplet dynamics was captured by including Continuum Surface force (CSF) approach suggested by Brackbill, Kothe, and Zemach (Journal of Computational Physics 1992, 100, 335). The shape and rise velocities predicted from model were in good agreement with experimental data. The results from simulations were used, to analyze the wake structure and pressure distribution around the droplet. It was found that the smaller droplets which ascended in rectilinear path were associated with an axisymmetric wakes whereas larger and intermediate sized droplets in high SDS concentration wobbled as they ascended because of asymmetric wakes.

Original language	English
Pages (from-to)	2098-2114
Number of pages	17
Journal	Canadian Journal of Chemical Engineering
Volume	92
Issue number	12
DOIs	https://doi.org/10.1002/cjce.22074
State	Published - 1 Dec 2014
Externally published	Yes

Keywords

Crude oil droplet
Interfacial tension
Internal circulations
Surfactant
VOF

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10.1002/cjce.22074

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@article{14440aa26f174b37b1e57903c61ef313,

title = "Effect of surfactant on the dynamics of a crude oil droplet in water column: Experimental and numerical investigation",

abstract = "In this study we have investigated the effect of surfactant, sodium dodecyl sulfate (SDS), on the dynamics of a single crude oil droplet, rising in a quiescent water column. Experiments were conducted in a tank, in which an oil droplet was released into a stagnant water column through a nozzle. The droplets ranging from 0.3 to 0.85cm were produced from three different sized nozzles. The shape adopted by the emanating droplets varied from spherical to oblate. SDS concentrations were varied from 0 to 750ppm in water. The adsorption of surfactant reduced the interfacial tension at oil-water interface which resulted in generation of smaller sized droplets at the nozzle and caused the droplet to flatten. Consequently, the rise velocities of droplets decreased. A numerical model based on finite volume method was developed using commercial CFD package ANSYS Fluent{\textregistered}. The model employed volume of fluid method, suggested by Hirt and Nichols (Journal of Computational Physics 1981, 39, 201), with an interface reconstruction technique based on piecewise linear representation for tracking the oil-water interface. The influence of surface tension on the droplet dynamics was captured by including Continuum Surface force (CSF) approach suggested by Brackbill, Kothe, and Zemach (Journal of Computational Physics 1992, 100, 335). The shape and rise velocities predicted from model were in good agreement with experimental data. The results from simulations were used, to analyze the wake structure and pressure distribution around the droplet. It was found that the smaller droplets which ascended in rectilinear path were associated with an axisymmetric wakes whereas larger and intermediate sized droplets in high SDS concentration wobbled as they ascended because of asymmetric wakes.",

keywords = "Crude oil droplet, Interfacial tension, Internal circulations, Surfactant, VOF",

author = "Abhijit Rao and Reddy, {Rupesh K.} and Franz Ehrenhauser and Krishnaswamy Nandakumar and Thibodeaux, {Louis J.} and Dandina Rao and Valsaraj, {Kalliat T.}",

note = "Publisher Copyright: {\textcopyright} 2014 Canadian Society for Chemical Engineering.",

year = "2014",

month = dec,

day = "1",

doi = "10.1002/cjce.22074",

language = "英语",

volume = "92",

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journal = "Canadian Journal of Chemical Engineering",

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TY - JOUR

T1 - Effect of surfactant on the dynamics of a crude oil droplet in water column

T2 - Experimental and numerical investigation

AU - Rao, Abhijit

AU - Reddy, Rupesh K.

AU - Ehrenhauser, Franz

AU - Nandakumar, Krishnaswamy

AU - Thibodeaux, Louis J.

AU - Rao, Dandina

AU - Valsaraj, Kalliat T.

PY - 2014/12/1

Y1 - 2014/12/1

N2 - In this study we have investigated the effect of surfactant, sodium dodecyl sulfate (SDS), on the dynamics of a single crude oil droplet, rising in a quiescent water column. Experiments were conducted in a tank, in which an oil droplet was released into a stagnant water column through a nozzle. The droplets ranging from 0.3 to 0.85cm were produced from three different sized nozzles. The shape adopted by the emanating droplets varied from spherical to oblate. SDS concentrations were varied from 0 to 750ppm in water. The adsorption of surfactant reduced the interfacial tension at oil-water interface which resulted in generation of smaller sized droplets at the nozzle and caused the droplet to flatten. Consequently, the rise velocities of droplets decreased. A numerical model based on finite volume method was developed using commercial CFD package ANSYS Fluent®. The model employed volume of fluid method, suggested by Hirt and Nichols (Journal of Computational Physics 1981, 39, 201), with an interface reconstruction technique based on piecewise linear representation for tracking the oil-water interface. The influence of surface tension on the droplet dynamics was captured by including Continuum Surface force (CSF) approach suggested by Brackbill, Kothe, and Zemach (Journal of Computational Physics 1992, 100, 335). The shape and rise velocities predicted from model were in good agreement with experimental data. The results from simulations were used, to analyze the wake structure and pressure distribution around the droplet. It was found that the smaller droplets which ascended in rectilinear path were associated with an axisymmetric wakes whereas larger and intermediate sized droplets in high SDS concentration wobbled as they ascended because of asymmetric wakes.

AB - In this study we have investigated the effect of surfactant, sodium dodecyl sulfate (SDS), on the dynamics of a single crude oil droplet, rising in a quiescent water column. Experiments were conducted in a tank, in which an oil droplet was released into a stagnant water column through a nozzle. The droplets ranging from 0.3 to 0.85cm were produced from three different sized nozzles. The shape adopted by the emanating droplets varied from spherical to oblate. SDS concentrations were varied from 0 to 750ppm in water. The adsorption of surfactant reduced the interfacial tension at oil-water interface which resulted in generation of smaller sized droplets at the nozzle and caused the droplet to flatten. Consequently, the rise velocities of droplets decreased. A numerical model based on finite volume method was developed using commercial CFD package ANSYS Fluent®. The model employed volume of fluid method, suggested by Hirt and Nichols (Journal of Computational Physics 1981, 39, 201), with an interface reconstruction technique based on piecewise linear representation for tracking the oil-water interface. The influence of surface tension on the droplet dynamics was captured by including Continuum Surface force (CSF) approach suggested by Brackbill, Kothe, and Zemach (Journal of Computational Physics 1992, 100, 335). The shape and rise velocities predicted from model were in good agreement with experimental data. The results from simulations were used, to analyze the wake structure and pressure distribution around the droplet. It was found that the smaller droplets which ascended in rectilinear path were associated with an axisymmetric wakes whereas larger and intermediate sized droplets in high SDS concentration wobbled as they ascended because of asymmetric wakes.

KW - Crude oil droplet

KW - Interfacial tension

KW - Internal circulations

KW - Surfactant

KW - VOF

UR - http://www.scopus.com/inward/record.url?scp=84910671500&partnerID=8YFLogxK

U2 - 10.1002/cjce.22074

DO - 10.1002/cjce.22074

M3 - 文章

AN - SCOPUS:84910671500

SN - 0008-4034

VL - 92

SP - 2098

EP - 2114

JO - Canadian Journal of Chemical Engineering

JF - Canadian Journal of Chemical Engineering

IS - 12

ER -

Effect of surfactant on the dynamics of a crude oil droplet in water column: Experimental and numerical investigation

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Keywords

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