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He Z, Tran H, Pack MY. Drop Bouncing Dynamics on Ultrathin Films. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:10135-10142. [PMID: 34379973 DOI: 10.1021/acs.langmuir.1c01510] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
For drops to contact various surfaces, the removal of the interstitial fluid is the prerequisite to contact. While the conventional understanding is for drops to irreversibly spread on a film made of the same substance, we describe the dynamics of drops initiating contact yet carrying enough momentum to completely lift off of the substrate which we label as contact bouncing. We report new experimental results of the dynamics between drops impacting thin films described by the ratio of the liquid film hL to the drop with diameter D0 for the range of 0.004 < hL/D0 < 0.08. Using high-speed interferometry, we visualize the interfacial gas layer spatiotemporal signatures across the various film thicknesses and Weber numbers. We find that while increasing the deformability of the thin films enhances the gas entrainment phenomenon at early times, it also increases the rate of the gas purging rate, increasing the chance of contact just prior to the gas film retraction and drop lift off sequence. Drops which contact the liquid film during the retraction stage are able to bounce with <5% volume loss.
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Affiliation(s)
- Ziwen He
- Department of Mechanical Engineering, Baylor University, One Bear Place #97356, Waco, Texas 76798, United States
| | - Huy Tran
- Department of Mechanical Engineering, Baylor University, One Bear Place #97356, Waco, Texas 76798, United States
| | - Min Y Pack
- Department of Mechanical Engineering, Baylor University, One Bear Place #97356, Waco, Texas 76798, United States
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Sharma M, Gopu M, George JE, Gupta S, Mampallil D. Drop impact on thin powder layers: pattern formation by air entrapment. SOFT MATTER 2020; 16:1342-1348. [PMID: 31934709 DOI: 10.1039/c9sm01887e] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
Impact of drops on thin powder layers displaces the powder particles radially outward producing shallow craters with thick rims, for example, as observed on dust layers on the floor. Here, we report that the patterns formed on thin powder layers by drop impact are not limited to such crater-like ones. Instead, depending upon the layer properties, disc or disc-plus-ring shaped patterns are formed at the impact point. We show that air entrapment and micro-bubble formation during the drop impact result in the formation of such patterns. Based on high-speed imaging, scaling analyses, and measurements with various liquids and powder layers, we propose a mechanism for the formation of such patterns. The phenomenon that we report can open further investigations on drop impact on the granular matter.
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Affiliation(s)
- Meenakshi Sharma
- Indian Institute of Science Education & Research Tirupati, Mangalam P. O. PIN 517507, Tirupati, AP, India.
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Marcotte F, Michon GJ, Séon T, Josserand C. Ejecta, Corolla, and Splashes from Drop Impacts on Viscous Fluids. PHYSICAL REVIEW LETTERS 2019; 122:014501. [PMID: 31012665 DOI: 10.1103/physrevlett.122.014501] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2018] [Revised: 10/11/2018] [Indexed: 06/09/2023]
Abstract
We investigate the impact of liquid drops on deep pools of aqueous glycerol solutions with variable pool viscosity and air pressure both experimentally and numerically. With this approach, we are able to address drop impacts on substrates that continuously transition from low-viscosity liquids to almost solids. We show that the generic corolla spreading out from the impact point consists of two distinct sheets, namely an ejecta sheet fed by the drop liquid and a second sheet fed by the substrate liquid, which evolve on separated timescales. These two sheets contribute to a varying extent to the corolla overall dynamics and splashing, depending on the viscosity ratio between the two liquids.
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Affiliation(s)
- Florence Marcotte
- Sorbonne Université, CNRS, Institut Jean Le Rond d'Alembert, F-75005 Paris, France
| | - Guy-Jean Michon
- Sorbonne Université, CNRS, Institut Jean Le Rond d'Alembert, F-75005 Paris, France
| | - Thomas Séon
- Sorbonne Université, CNRS, Institut Jean Le Rond d'Alembert, F-75005 Paris, France
| | - Christophe Josserand
- Laboratoire d'Hydrodynamique (LadHyX), UMR7646 CNRS-Ecole Polytechnique, 91128 Palaiseau CEDEX, France
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Che Z, Matar OK. Impact of droplets on immiscible liquid films. SOFT MATTER 2018; 14:1540-1551. [PMID: 29350232 DOI: 10.1039/c7sm02089a] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
The impact of droplets on liquid films is a ubiquitous phenomenon not only in nature but also in many industrial applications. Compared to the widely-studied impact of droplets on films of identical fluids, the impact of droplets on immiscible films has received far less attention. In the present work, we show using high-speed imaging that immiscibility has a profound effect on the impact dynamics. The impact of a water droplet on an oil film leads to the formation of a compound crown followed by a central jet, whereas that of an oil droplet on a water film results in rapid spreading on the film surface driven by a large, positive spreading factor. In the former scenario, the central jet occurs due to the severe stretching of the droplet during the formation of the crown and then the retraction of the droplet by capillarity, which leads to the collision of fluid at the impact point. A model for the elongation dynamics of the central jet is proposed based on energy conservation. The effects of key parameters controlling the impact process are analysed, including the droplet Ohnesorge and Weber numbers, the viscosity ratio, and the dimensionless film thickness. Different impact outcomes are discussed, such as bouncing, deposition, and oscillation of the impact droplet, the formation and collapse of the compound crown, and the formation and tip-pinching of the central jet. This study not only provides physical insights into the impact dynamics, but could also facilitate the control and optimisation of the droplet impact process in a number of applications as highlighted herein.
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Affiliation(s)
- Zhizhao Che
- State Key Laboratory of Engines, Tianjin University, Tianjin, 300072, China.
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Che Z, Matar OK. Impact of Droplets on Liquid Films in the Presence of Surfactant. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:12140-12148. [PMID: 28771014 DOI: 10.1021/acs.langmuir.7b01901] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The impact of droplets on liquid films is ubiquitous in natural and industrial processes, and surfactants can significantly alter the impact process by changing the local surface tension. Here we study the impact of droplets on liquid films in the presence of surfactant using high-speed photography, and reveal the flow pattern by dye-tracing. The effects of the droplet size and speed, and the initial film thickness on the impact process are elucidated. The results show that the flow is significantly affected by adding surfactant to the droplet, the liquid film, or to both phases. In particular, the film dye patterns form concentric circles and flower-shaped structures at low and high droplet Weber numbers, respectively. We also show how surfactant-induced Marangoni stresses modify these flow patterns, and alter the characteristics of the phenomena associated with the impact process, such as the propagation of capillary waves, the evolution of the crown, and the formation of secondary droplets. During the impact of surfactant droplets on thin water films, the Marangoni stresses can be sufficiently strong so as to drive film dewetting.
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Affiliation(s)
- Zhizhao Che
- State Key Laboratory of Engines, Tianjin University , Tianjin, 300072, China
- Department of Chemical Engineering, Imperial College London , London, SW7 2AZ, United Kingdom
| | - Omar K Matar
- Department of Chemical Engineering, Imperial College London , London, SW7 2AZ, United Kingdom
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Liu T, Xu X, Nadermann N, He Z, Jagota A, Hui CY. Interaction of Droplets Separated by an Elastic Film. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:75-81. [PMID: 27997205 DOI: 10.1021/acs.langmuir.6b03600] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The Laplace pressure of a droplet placed on one side of an elastic thin film can cause significant deformation in the form of a bulge on its opposite side. Here, we show that this deformation can be detected by other droplets suspended on the opposite side of the film, leading to interaction between droplets separated by the solid (but deformable) film. The interaction is repulsive when the drops have a large overlap and attractive when they have a small overlap. Thus, if two identical droplets are placed right on top of each other (one on either side of the thin film), they tend to repel each other, eventually reaching an equilibrium configuration where there is a small overlap. This observation can be explained by analyzing the energy landscape of the droplets interacting via an elastically deformed film. We further demonstrate this idea by designing a pattern comprising a big central drop with satellite droplets. This phenomenon can lead to techniques for directed motion of droplets confined to one side of a thin elastic membrane by manipulations on the other side.
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Affiliation(s)
| | | | - Nichole Nadermann
- Department of Chemical & Biomolecular Engineering and Bioengineering Program, Lehigh University , 111 Research Drive, Bethlehem, Pennsylvania 18015, United States
| | - Zhenping He
- Department of Chemical & Biomolecular Engineering and Bioengineering Program, Lehigh University , 111 Research Drive, Bethlehem, Pennsylvania 18015, United States
| | - Anand Jagota
- Department of Chemical & Biomolecular Engineering and Bioengineering Program, Lehigh University , 111 Research Drive, Bethlehem, Pennsylvania 18015, United States
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Lee C, Kim H, Nam Y. Drop impact dynamics on oil-infused nanostructured surfaces. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 30:8400-8407. [PMID: 24976266 DOI: 10.1021/la501341x] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
We experimentally investigated the impact dynamics of a water drop on oil-infused nanostructured surfaces using high-speed microscopy and scalable metal oxide nano surfaces. The effects of physical properties of the oil and impact velocity on complex fluid dynamics during drop impact were investigated. We show that the oil viscosity does not have significant effects on the maximal spreading radius of the water drop, while it moderately affects the retraction dynamics. The oil viscosity also determines the stability of the infused lubricant oil during the drop impact; i.e., the low viscosity oil layer is easily displaced by the impacting drop, which is manifested by a residual mark on the impact region and earlier initiation of prompt splashing. Also, because of the liquid (water)-liquid (oil) interaction on oil-infused surfaces, various instabilities are developed at the rim during impact under certain conditions, resulting in the flower-like pattern during retraction or elongated filaments during spreading. We believe that our findings will contribute to the rational design of oil-infused surfaces under drop impact conditions by illuminating the complex fluid phenomena on oil-infused surfaces during drop impact.
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Affiliation(s)
- Choongyeop Lee
- School of Aerospace and Mechanical Engineering, Korea Aerospace University , Goyang 412-791, Korea
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Berraquero CP, Maurel A, Petitjeans P, Pagneux V. Experimental realization of a water-wave metamaterial shifter. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2013; 88:051002. [PMID: 24329207 DOI: 10.1103/physreve.88.051002] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2012] [Revised: 05/21/2013] [Indexed: 06/03/2023]
Abstract
We demonstrate by quantitative experimental measurements that metamaterials with anisotropic properties can be used in the context of water waves to produce a reflectionless bent waveguide. The anisotropic medium consists in a bathymetry with subwavelength layered structure that shifts the wave in the direction of the waveguide bending (10°, 20°, and 30°). The waveguide filled with such metamaterial is tested experimentally and compared to a reference empty bent waveguide. The experimental method used to characterize the wave field allows for space-time resolved measurements of water elevation. Results show the efficiency of the shifter. Modal treatment of the experimental data confirms that the metamaterial prevents higher modes from being excited in the waveguide.
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Affiliation(s)
- C P Berraquero
- Blackett Laboratory, Imperial College London, London SW7 2AZ, United Kingdom
| | - A Maurel
- Institut Langevin LOA, UMR CNRS 7587-ESPCI, 5 rue Jussieu, 75005 Paris, France
| | - P Petitjeans
- Laboratoire de Physique et Mécanique des Milieux Hétérogènes (PMMH), UMR CNRS 7636-ESPCI-UPMC Univ. Paris 6-UPD Univ. Paris 7, 10 rue Vauquelin, 75005 Paris, France
| | - V Pagneux
- Laboratoire d'Acoustique de l'Université du Maine, UMR CNRS 6613, Avenue Olivier Messiaen, 72085 Le Mans, France
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Le Goff A, Cobelli P, Lagubeau G. Supershear Rayleigh waves at a soft interface. PHYSICAL REVIEW LETTERS 2013; 110:236101. [PMID: 25167515 DOI: 10.1103/physrevlett.110.236101] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/05/2013] [Revised: 02/22/2013] [Indexed: 05/10/2023]
Abstract
We report on the experimental observation of waves at a liquid foam surface propagating faster than the bulk shear waves. The existence of such waves has long been debated, but the recent observation of supershear events in a geophysical context has inspired us to search for their existence in a model viscoelastic system. An optimized fast profilometry technique allows us to observe on a liquid foam surface the waves triggered by the impact of a projectile. At high impact velocity, we show that the expected subshear Rayleigh waves are accompanied by faster surface waves that can be identified as supershear Rayleigh waves.
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Affiliation(s)
- Anne Le Goff
- Microfluidique, MEMs et Nanostructures, UMR Gulliver 7083, ESPCI, 75005 Paris, France
| | - Pablo Cobelli
- Departamento de Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires and IFIBA, CONICET, Ciudad Universitaria, 1428 Buenos Aires, Argentina and Physique et Mécanique des Milieux Hétérogènes PMMH, UMR CNRS 7636, ESPCI, UMPC Université Paris 6, UPD Université Paris 7, Paris, France
| | - Guillaume Lagubeau
- Physique et Mécanique des Milieux Hétérogènes PMMH, UMR CNRS 7636, ESPCI, UMPC Université Paris 6, UPD Université Paris 7, Paris, France and Departamento de Física, Universidad de Santiago de Chile, Santiago, Chile
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