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Reddy M, Basavaraj MG, Thampi SP. Dynamics of spreading of an asymmetrically placed droplet near a fluid-fluid interface. SOFT MATTER 2024; 20:2986-2997. [PMID: 38477133 DOI: 10.1039/d3sm00685a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/14/2024]
Abstract
Two-dimensional numerical simulations are carried out to study the spreading dynamics of a droplet placed in the vicinity of a fluid-fluid interface. Simulations are performed using the hybrid lattice-Boltzmann technique and the diffuse-interface model by considering three immiscible fluids of the same density and viscosity. In contrast to the well-studied spreading of drops placed symmetrically across fluid-fluid interfaces, this work considers the simultaneous migration, spreading and eventual adsorption of an asymmetrically placed drop. These processes, which are solely driven by interfacial forces, are characterised by monitoring the temporal evolution of geometric parameters, such as the centre of mass, radius and height of the drop, the surface energy of the three interfaces and the associated flow fields inside and outside the droplet. The rate of spreading and rate of adsorption are also calculated to determine the dominant processes that drive the dynamics of the system.
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Affiliation(s)
- Madhurima Reddy
- Department of Chemical Engineering, Indian Institute of Technology Madras, Chennai 600036, India.
| | - Madivala G Basavaraj
- Department of Chemical Engineering, Indian Institute of Technology Madras, Chennai 600036, India.
| | - Sumesh P Thampi
- Department of Chemical Engineering, Indian Institute of Technology Madras, Chennai 600036, India.
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Hazra S, Mitra S, Sen AK. Migration and Spreading of Droplets across a Fluid-Fluid Interface in Microfluidic Coflow. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:9660-9668. [PMID: 35876791 DOI: 10.1021/acs.langmuir.2c01260] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Interfacial migration of droplets in microfluidic confinements has significant relevance in cell biology and biochemical assays. So far, studies on passive interfacial migration of droplets are limited to co-flow interfaces having small interfacial tension (IFT ∼ 1 mN/m). Here, we elucidate the migration and spreading of droplets (SiO-1000, SiO-100, FC40, and castor oil as phase 3, P3) across the interface between a pair of coflowing streams (PEG as P1, SiO-100, SiO-20, FC40, and olive oil as P2) having large IFT (∼10 mN/m), with the three different phases immiscible. Interfacial migration involving interfaces of large IFT is facilitated by confining droplets between the channel wall and coflow interface. We find that contact between droplets and the coflow interface is governed by the confinement ratio (i.e., the ratio of drop size to stream width) and the ratio of the capillary numbers of the coflowing streams. Depending on the sign of the spreading parameter (S) of the co-flowing phases, droplet migration or spreading at the interface is observed. While interfacial migration is observed for S1 < 0 and S2 > 0, droplet spreading is observed for S1 < 0 and S2 < 0, where S1 and S2 are P1 and P2 side spreading parameters, respectively. We investigate the droplet migration dynamics and time evolution of the contact line and the interface. Our results show that the speed of interfacial migration increases with increasing spreading parameter contrast between the coflowing phases. In the droplet spreading case, we experimentally study the variation in the spreading length with time, revealing three distinct regimes in good agreement with predictions from analytical scaling. Our study explores the interfacial transport of droplets involving high IFT interfaces, advancing the fundamental understanding of the topic that may find relevance in droplet microfluidics.
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Affiliation(s)
- Shamik Hazra
- Fluid Systems Laboratory, Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai, 600036 Tamilnadu, India
| | - Sushanta Mitra
- Waterloo Institute for Nanotechnology, Department of Mechanical & Mechatronics Engineering, University of Waterloo, Waterloo, N2L 3G1 Ontario, Canada
| | - Ashis Kumar Sen
- Fluid Systems Laboratory, Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai, 600036 Tamilnadu, India
- Micro Nano Bio-Fluidics Group, Indian Institute of Technology Madras, Chennai, 600036 Tamilnadu, India
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Kulkarni V, Lolla VY, Tamvada SR, Shirdade N, Anand S. Coalescence and spreading of drops on liquid pools. J Colloid Interface Sci 2020; 586:257-268. [PMID: 33187667 DOI: 10.1016/j.jcis.2020.10.089] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2020] [Revised: 09/30/2020] [Accepted: 10/17/2020] [Indexed: 02/03/2023]
Abstract
HYPOTHESIS Oil spills have posed a serious threat to our marine and ecological environment in recent times. Containment of spills proliferating via small drops merging with oceans/seas is especially difficult since their mitigation is closely linked to the coalescence dependent spreading. This inter-connectivity and its dependence on the physical properties of the drop has not been explored until now. Furthermore, pinch-off behavior and scaling laws for such three-phase systems have not been reported. EXPERIMENTS We investigate the problem of gentle deposition of a single drop of oil on a pool of water, representative of an oil spill scenario. Methodical study of 11 different n-alkanes, polymers and hydrocarbons with varying viscosity and initial spreading coefficients is conducted. Regime map, scaling laws for deformation features and spreading behavior are established. FINDINGS The existence of a previously undocumented regime of delayed coalescence is reported. A novel application of the inertia-visco-capillary (I-V-C) scale collapses all experimental coalescence data on a single line while the early stage spreading is found to be either oscillatory or asymptotically reaching a constant value, depending on the viscosity of the oil drop unlike the well documented monotonic, power law late-time spreading behavior. These findings are equally applicable to applications like emulsions and enhanced oil recovery.
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Affiliation(s)
- Varun Kulkarni
- Department of Mechanical & Industrial Engineering, University of Illinois at Chicago, Chicago, IL 60607, United States.
| | - Venkata Yashasvi Lolla
- Department of Mechanical & Industrial Engineering, University of Illinois at Chicago, Chicago, IL 60607, United States; Department of Mechanical Engineering, Virginia Polytechnic Institute and State University, Blacksburg, VA 24060, United States
| | - Suhas Rao Tamvada
- Department of Mechanical & Industrial Engineering, University of Illinois at Chicago, Chicago, IL 60607, United States
| | - Nikhil Shirdade
- Department of Mechanical & Industrial Engineering, University of Illinois at Chicago, Chicago, IL 60607, United States
| | - Sushant Anand
- Department of Mechanical & Industrial Engineering, University of Illinois at Chicago, Chicago, IL 60607, United States.
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Jia X, Luo Y, Huang R, Bo H, Liu Q, Zhu X. Spreading kinetics of fluorocarbon surfactants on several liquid fuels surfaces. Colloids Surf A Physicochem Eng Asp 2020. [DOI: 10.1016/j.colsurfa.2020.124441] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Koldeweij RBJ, van Capelleveen BF, Lohse D, Visser CW. Marangoni-driven spreading of miscible liquids in the binary pendant drop geometry. SOFT MATTER 2019; 15:8525-8531. [PMID: 31592523 DOI: 10.1039/c8sm02074d] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
When two liquids with different surface tensions come into contact, the liquid with lower surface tension spreads over the other liquid. This Marangoni-driven spreading has been studied for various geometries and surfactants, but the dynamics of miscible liquids in the binary geometry (drop-drop) has hardly been investigated. Here we use stroboscopic illumination by nanosecond laser pulses to temporally resolve the distance L(t) over which a low-surface-tension drop spreads over a miscible high-surface-tension drop. L(t) is measured as a function of time, t, for various surface tension differences between the liquids and for various viscosities, revealing a power-law L(t) ∼ tα with a spreading exponent α ≈ 0.75. This value is consistent with previous results for viscosity-limited spreading over a deep bath. The universal power law L[combining tilde] ∝ t[combining tilde]3/4 that describes the dimensionless distance L[combining tilde] as a function of the dimensionless time t[combining tilde] reasonably captures our experiments, as well as previous experiments for different geometries, miscibilities, and surface tension modifiers (solvents and surfactants). The range of this power law remarkably covers ten orders of magnitude in dimensionless time. This result enables engineering of drop encapsulation for various liquid-liquid systems.
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Affiliation(s)
- Robin B J Koldeweij
- Physics of Fluids Group & Max Planck Center Twente for Complex Fluid Dynamics, Department of Science and Technology, J. M. Burgers Center for Fluid Dynamics, University of Twente, 7500 AE Enschede, The Netherlands.
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Tsuchitani S, Fukutake T, Mukai D, Miki H, Kikuchi K. Unstable Spreading of Ionic Liquids on an Aqueous Substrate. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:11040-11046. [PMID: 28949148 DOI: 10.1021/acs.langmuir.7b01799] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The spontaneous spreading of thin liquid films over substrate surfaces is attracting much attention due to its broad applications. Under particular conditions, surfactants deposited on substrates exhibit unstable spreading. In spite of the large effects of the stability of the spreading on the accuracy and efficiency of industrial processes that use the spreading, understanding how the stability of the spreading process is governed by the physical and chemical properties of the system is still little known. Recently, ionic liquids have been characterized as a new kind of surfactant due to their special properties. Here, we investigate the stability of the spreading of deposited imidazolium-based ionic liquids on an aqueous substrate. We focus mainly on the effects that the water solubility of the ionic liquids has on the stability. Hydrophobic ionic liquids exhibit spreading that has a highly periodic and petal-like unstable spreading front, whereas hydrophilic ionic liquids spread without such a regular spreading front and their spreading area shrinks after reaching its maximum. We propose a model for the generation of unstable spreading of hydrophobic ionic liquids, i.e., the unstable spreading front is created by the penetration of oncoming water in front of the spreading tip into the more viscous spreading ionic liquid layer, like the viscous fingering that occurs in a Hele-Shaw cell. However, the direction of the penetration is the opposite of the direction that the interface moves (the spreading direction), which is contrary to that in viscous fingering.
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Affiliation(s)
- Shigeki Tsuchitani
- Faculty of Systems Engineering, Department of Opto-mechatronics, ‡Graduate School of Systems Engineering, Wakayama University , 930 Sakaedani, Wakayama 640-8510, Japan
| | - Taiga Fukutake
- Faculty of Systems Engineering, Department of Opto-mechatronics, ‡Graduate School of Systems Engineering, Wakayama University , 930 Sakaedani, Wakayama 640-8510, Japan
| | - Daiki Mukai
- Faculty of Systems Engineering, Department of Opto-mechatronics, ‡Graduate School of Systems Engineering, Wakayama University , 930 Sakaedani, Wakayama 640-8510, Japan
| | - Hirofumi Miki
- Faculty of Systems Engineering, Department of Opto-mechatronics, ‡Graduate School of Systems Engineering, Wakayama University , 930 Sakaedani, Wakayama 640-8510, Japan
| | - Kunitomo Kikuchi
- Faculty of Systems Engineering, Department of Opto-mechatronics, ‡Graduate School of Systems Engineering, Wakayama University , 930 Sakaedani, Wakayama 640-8510, Japan
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Semakov AV, Kulichikhin VG, Malkin AY. Phase separation of polymer solutions on a solvent surface. COLLOID JOURNAL 2017. [DOI: 10.1134/s1061933x17020144] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Dardelle G, Erni P. Three-phase interactions and interfacial transport phenomena in coacervate/oil/water systems. Adv Colloid Interface Sci 2014; 206:79-91. [PMID: 24268195 DOI: 10.1016/j.cis.2013.10.001] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2013] [Accepted: 10/01/2013] [Indexed: 11/19/2022]
Abstract
Complex coacervation is an associative liquid/liquid phase separation resulting in the formation of two liquid phases: a polymer-rich coacervate phase and a dilute continuous solvent phase. In the presence of a third liquid phase in the form of disperse oil droplets, the coacervate phase tends to wet the oil/water interface. This affinity has long been known and used for the formation of core/shell capsules. However, while encapsulation by simple or complex coacervation has been used empirically for decades, there is a lack of a thorough understanding of the three-phase wetting phenomena that control the formation of encapsulated, compound droplets and the role of the viscoelasticity of the biopolymers involved. In this contribution, we review and discuss the interplay of wetting phenomena and fluid viscoelasticity in coacervate/oil/water systems from the perspective of colloid chemistry and fluid dynamics, focusing on aspects of rheology, interfacial tension measurements at the coacervate/solvent interface, and on the formation and fragmentation of three-phase compound drops.
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Affiliation(s)
- Gregory Dardelle
- Firmenich SA, Corporate Research Division, Materials Science Department, 1217 Meyrin, Geneva, Switzerland
| | - Philipp Erni
- Firmenich SA, Corporate Research Division, Materials Science Department, 1217 Meyrin, Geneva, Switzerland.
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Sinz DK, Hanyak M, Darhuber AA. Immiscible surfactant droplets on thin liquid films: Spreading dynamics, subphase expulsion and oscillatory instabilities. J Colloid Interface Sci 2011; 364:519-29. [DOI: 10.1016/j.jcis.2011.08.055] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2011] [Revised: 07/19/2011] [Accepted: 08/21/2011] [Indexed: 12/01/2022]
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Sinz DKN, Hanyak M, Zeegers JCH, Darhuber AA. Insoluble surfactant spreading along thin liquid films confined by chemical surface patterns. Phys Chem Chem Phys 2011; 13:9768-77. [DOI: 10.1039/c0cp02135k] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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McBride JF, Cary JW, Simmons C. Direct measurement of the spreading pressure of organic liquids on water. J Colloid Interface Sci 1989. [DOI: 10.1016/0021-9797(89)90251-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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