scholarly journals Effects of a surfactant monolayer on the measurement of equilibrium interfacial tension of a drop in extensional flow

2009 ◽  
Vol 333 (2) ◽  
pp. 570-578 ◽  
Author(s):  
Andrés González-Mancera ◽  
Vijay Kumar Gupta ◽  
Mustapha Jamal ◽  
Charles D. Eggleton
Keyword(s):  
Interfacial Tension ◽  
Extensional Flow

scholarly journals Interfacial Tension Measurements in Microfluidic Quasi-Static Extensional Flows

Micromachines ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 272
Author(s):  
Doojin Lee ◽  
Amy Q. Shen
Keyword(s):  
Interfacial Tension ◽  
Microfluidic Device ◽  
Extensional Flow ◽  
Immiscible Fluids ◽  
Droplet Microfluidics ◽  
Channel Height ◽  
Deformation Model ◽  
Droplet Deformation ◽  
Extensional Flows ◽  
2D Model

Droplet microfluidics provides a versatile tool for measuring interfacial tensions between two immiscible fluids owing to its abilities of fast response, enhanced throughput, portability and easy manipulations of fluid compositions, comparing to conventional techniques. Purely homogeneous extension in the microfluidic device is desirable to measure the interfacial tension because the flow field enables symmetric droplet deformation along the outflow direction. To do so, we designed a microfluidic device consisting of a droplet production region to first generate emulsion droplets at a flow-focusing area. The droplets are then trapped at a stagnation point in the cross junction area, subsequently being stretched along the outflow direction under the extensional flow. These droplets in the device are either confined or unconfined in the channel walls depending on the channel height, which yields different droplet deformations. To calculate the interfacial tension for confined and unconfined droplet cases, quasi-static 2D Darcy approximation model and quasi-static 3D small deformation model are used. For the confined droplet case under the extensional flow, an effective viscosity of the two immiscible fluids, accounting for the viscosity ratio of continuous and dispersed phases, captures the droplet deformation well. However, the 2D model is limited to the case where the droplet is confined in the channel walls and deforms two-dimensionally. For the unconfined droplet case, the 3D model provides more robust estimates than the 2D model. We demonstrate that both 2D and 3D models provide good interfacial tension measurements under quasi-static extensional flows in comparison with the conventional pendant drop method.

A Long Wavelength Model for Manufacturing of Continuous Metal Microwires by Thermal Fiber Drawing From a Preform

2017 ◽  
Vol 6 (1) ◽  
Author(s):  
Jingzhou Zhao ◽  
Xiaochun Li
Keyword(s):  
Interfacial Tension ◽  
Molten Metal ◽  
Capillary Number ◽  
Extensional Flow ◽  
Tension Stress ◽  
Core Diameter ◽  
Manufacturing Method ◽  
Long Wavelength ◽  
Thermal Drawing ◽  
Continuous Metal

Thermal drawing from a preform recently emerges as a scalable manufacturing method for the high volume production of continuous metal microwires for numerous applications. However, no model can yet satisfactorily provide effective understanding of core diameter and continuity from process parameters and material properties during thermal drawing. In this paper, a long wavelength model is derived to describe the dynamics of a molten metal micro-jet entrained within an immiscible, viscous, nonlinear free surface extensional flow. The model requires numerical data (e.g., drawing force and cladding profile) be measured in real time. Examination of the boundary conditions reveals that the diameter control mechanism is essentially volume conservation. The flow rate of molten metal is controlled upstream while the flow velocity is controlled downstream realized by solidification of the molten metal. The dynamics of the molten metal jet are found to be dominated by interfacial tension, stress in the cladding, and pressure in the molten metal. Taylor's conical fluid interface solution (Taylor, 1966, “Conical Free Surfaces and Fluid Interfaces,” Applied Mechanics, Springer, Berlin, pp. 790–796.) is found to be a special case of this model. A dimensionless capillary number Ca=2Fa/γA(0) is suggested to be used as the indicator for the transition from continuous mode (i.e., viscous stress dominating) to dripping mode (i.e., interfacial tension dominating). Experimental results showed the existence of a critical capillary number Cacr, above which continuous metal microwires can be produced, providing the first ever quantitative predictor of the core continuity during preform drawing of metal microwires.

Spindle-shaped drops in a viscous extensional flow

1981 ◽  
Vol 90 (3) ◽  
pp. 529-536 ◽  
Author(s):  
J. D. Sherwood
Keyword(s):  
Reynolds Number ◽  
Interfacial Tension ◽  
Extensional Flow ◽  
Fluid Motion ◽  
Normal Stresses ◽  
Hydrodynamic Stress ◽  
Drop Shape ◽  
Accurate Representation ◽  
Reynolds Number Flow ◽  
Number Flow

We study the deformation of a long slender drop of viscosity ζμ suspended in another liquid of viscosity μ. Interfacial tension causes the drop to become spherical when there is no fluid motion. When the flow is weak the drop is slightly perturbed, and this case was studied by Taylor (7). Computing the flow around an exact sphere, he used the resulting imbalance in the normal stresses to predict the perturbed drop shape. When the drop is in viscid or slightly viscous (ζ ≪ 1), and when the flow is stronger, the drop becomes long and slender. Previous slender-body analyses (Taylor (8) Buckmaster (2, 3), Acrivos & Lo(1) and Hinch & Acrivos(5)) predict pointed ends, but break down in the neighbourhood of these ends. Here we adopt an approach similar to that of Taylor (7). The zero Reynolds number flow around a spindle-shaped drop with pointed ends is computed exactly. Interfacial tension does not quite balance the hydrodynamic stress, and the resulting imbalance in the normal stresses is used to predict a more accurate representation of the drop shape.

Deformation of a two-dimensional drop at non-zero Reynolds number in time-periodic extensional flows: numerical simulation

2001 ◽  
Vol 436 ◽  
pp. 177-206 ◽  
Author(s):  
KAUSIK SARKAR ◽  
WILLIAM R. SCHOWALTER
Keyword(s):  
Reynolds Number ◽  
Interfacial Tension ◽  
Vortex Flow ◽  
Extensional Flow ◽  
Reynolds Numbers ◽  
Time Dependent ◽  
Drop Deformation ◽  
Two Dimensional ◽  
Extensional Flows ◽  
Potential Vortex

The shape of a two-dimensional viscous drop deforming in several time-dependent flow fields, including that due to a potential vortex, has been studied. Vortex flow was approximated by linearizing the induced velocity field at the drop centre, giving rise to an extensional flow with rotating axes of stretching. A generalization of the potential vortex, a flow we have called rotating extensional flow, occurs when the frequency of revolution of the flow is varied independently of the shear rate. Drops subjected to this forcing flow exhibit an interesting resonance phenomenon. Finally we have studied drop deformation in an oscillatory extensional flow.Calculations were performed at small but non-zero Reynolds numbers using an ADI front-tracking/finite difference method. We investigate the effects of interfacial tension, periodicity, viscosity ratio, and Reynolds number on the drop dynamics. The simulation reveals interesting behaviour for steady stretching flows, as well as time-dependent flows. For a steady extensional flow, the drop deformation is found to be non-monotonic with time in its approach to an equilibrium value. At sufficiently high Reynolds numbers, the drop experiences multiple growth–collapse cycles, with possible axes reversal, before reaching a final shape. For a vortex flow, the long-time deformation reaches a steady value, and the drop attains a revolving steady elliptic shape. For rotating extensional flows as well as oscillatory extensional flows, the maximum value of deformation displays resonance with variation in parameters, first increasing and then decreasing with increasing interfacial tension or forcing frequency. A simple ODE model with proper forcing is offered to explain the observed phenomena.

Perbandingan Karakteristik Surfaktan Metil Ester Sulfonat dan Sodium Lauril Sulfonat sebagai Bahan Emulsifier

2016 ◽  
Vol 9 (2) ◽  
pp. 167-176
Author(s):  
Eldha Sampepana ◽  
Paluphy Eka Yustini ◽  
Aditya Rinaldi ◽  
Amiroh Amiroh
Keyword(s):  
Fatty Acids ◽  
Surface Tension ◽  
Methyl Ester ◽  
Interfacial Tension ◽  
Palm Oil ◽  
Emulsion Stability ◽  
Raw Material ◽  
Enzymatic Method

Surfactant which is used as raw emulsifier in an industry activity such as Sodium Lauryl Sulfonate is a raw material import, it is petroleum derivative which is not renewable and may cause pollution to the environment, because it is not degraded and are carcinogenic. The purpose of the research is to compare the characteristics of the Quaternary methyl ester sulfonat (MES) and Sodium Lauryl Sulfonat (SLS) as emulsifier. First, make the MES by filtering and eliminating fatty acids of palm oil, then process the MES with enzymatic method become methyl ester, then react it in sulfonation and metanolization process, and also neutralized with NaOH. Next, the MES experiment is compared with SLS and existing MES in the market. The results show that surfactants MES experiment has value hidrofil lipofil balance (HLB) interfacial tension and emulsion stability greater than MES in the market and SLS. And the surface tension of MES experiment is larger than MES in the market, but smaller compared to SLS.ABSTRAKSurfaktan yang digunakan sebagai bahan baku emulsifer dalam aktivitas suatu industri pada saat ini seperti Sodium Lauril Sulfonat  merupakan bahan baku import yang merupakan turunan dari minyak bumi, dengan sifat tidak dapat diperbaharui dan dapat menimbulkan pencemaran terhadap lingkungan karena tidak mudah terdegradasi serta bersifat karsinogenik. Metil ester sulfonat dari bahan minyak sawit merupakan surfaktan dengan sifat mudah terdegradasi yang perlu diketahui karakteristiknya. Penelitian bertujuan untuk membandingkan karakteristik surfaktan metil ester sulfonat (MES) dan Sodium Lauril Sulfonat (SLS) sebagai bahan emulsifier. Mula-mula dilakukan pembuatan MES dengan cara menyaring dan menghilangkan asam lemak minyak sawit terlebih dahulu, kemudian diolah menjadi metil ester secara enzimatis, lalu direaksikan secara sulfonasi dan metanolisis, serta dinetralkan dengan NaOH. Selanjutnya MES hasil percobaan dibandingkan dengan SLS dan MES yang ada dipasaran. Hasil penelitian menunjukkan bahwa surfaktan MES memiliki nilai hidrofil lipofil balance (HLB) tegangan antar muka dan stabilitas emulsi lebih besar apabila dibandingkan dengan MES di pasaran dan SLS, kecuali nilai stabilitas emulsi antara MES dan SLS sama. Dan tegangan permukaan MES hasil percobaan, lebih besar dibandingkan dengan MES dipasaran, dan lebih kecil dibandingkan dengan SLS. Kata kunci :   Metil  ester sulfonat, hidrofil lipofil balance, emulsifier, sodium lauril sulfonat , stabilitas emulsi 

Ultra-Low Interfacial Tension of a Surfactant under a Wide Range of Temperature and Salinity Conditions for Chemical Enhanced Oil Recovery

2018 ◽  
Vol 55 (3) ◽  
pp. 252-257 ◽  
Author(s):  
Derong Xu ◽  
Wanli Kang ◽  
Liming Zhang ◽  
Jiatong Jiang ◽  
Zhe Li ◽  
...  
Keyword(s):  
Interfacial Tension ◽  
Enhanced Oil Recovery ◽  
Oil Recovery ◽  
Wide Range ◽  
Low Interfacial Tension

Phase Inversion in Two-Phase Liquid Systems

1992 ◽  
Vol 57 (7) ◽  
pp. 1419-1423
Author(s):  
Jindřich Weiss
Keyword(s):  
Interfacial Tension ◽  
Phase Inversion ◽  
Continuous Phase ◽  
Considerable Effect ◽  
Weak Dependence ◽  
Dispersed Phase ◽  
Two Phase ◽  
Liquid Systems ◽  
Phase Liquid

New data on critical holdups of dispersed phase were measured at which the phase inversion took place. The systems studied differed in the ratio of phase viscosities and interfacial tension. A weak dependence was found of critical holdups on the impeller revolutions and on the material contactor; on the contrary, a considerable effect of viscosity was found out as far as the viscosity of continuous phase exceeded that of dispersed phase.

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