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Shah P, Driscoll MM. Drop impact dynamics of complex fluids: a review. SOFT MATTER 2024; 20:4839-4858. [PMID: 38873962 DOI: 10.1039/d4sm00145a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2024]
Abstract
The impact of fluid drops on solid substrates has widespread interest in many industrial coating and spraying applications, such as ink-jet printing and agricultural pesticide sprays. Many of the fluids used in these applications are non-Newtonian, that is they contain particulate or polymeric additives that strongly modify their flow behaviour. While a large body of experimental and theoretical work has been done to understand the impact dynamics of Newtonian fluids, we as a community have much progress to make to understand how these dynamics are modified when the impact fluid has non-Newtonian rheology. In this review, we outline recent experimental, theoretical, and computational advances in the study of impact dynamics of complex fluids on solid surfaces. Here, we provide an overview of this field that is geared towards a multidisciplinary audience. Our discussion is segmented by two principal material constitutions: polymeric fluids and particulate suspensions. Throughout, we highlight promising future directions, as well as ongoing experimental and theoretical challenges in the field.
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Affiliation(s)
- Phalguni Shah
- Department of Physics and Astronomy, Northwestern University, Evanston, IL, USA.
| | - Michelle M Driscoll
- Department of Physics and Astronomy, Northwestern University, Evanston, IL, USA.
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Milani M, Phou T, Prevot G, Ramos L, Cipelletti L. Space-resolved dynamic light scattering within a millimeter-sized drop: From Brownian diffusion to the swelling of hydrogel beads. Phys Rev E 2024; 109:064613. [PMID: 39021030 DOI: 10.1103/physreve.109.064613] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2024] [Accepted: 05/06/2024] [Indexed: 07/20/2024]
Abstract
We present a dynamic light scattering setup to probe, with time and space resolution, the microscopic dynamics of soft matter systems confined within millimeter-sized spherical drops. By using an ad hoc optical layout, we tackle the challenges raised by refraction effects due to the unconventional shape of the samples. We first validate the setup by investigating the dynamics of a suspension of Brownian particles. The dynamics measured at different positions in the drop, and hence different scattering angles, are found to be in excellent agreement with those obtained for the same sample in a conventional light scattering setup. We then demonstrate the setup capabilities by investigating a bead made of a polymer hydrogel undergoing swelling. The gel microscopic dynamics exhibit a space dependence that strongly varies with time elapsed since the beginning of swelling. Initially, the dynamics in the periphery of the bead are much faster than in the core, indicative of nonuniform swelling. As the swelling proceeds, the dynamics slow down and become more spatially homogeneous. By comparing the experimental results to numerical and analytical calculations for the dynamics of a homogeneous, purely elastic sphere undergoing swelling, we establish that the mean square displacement of the gel strands deviates from the affine motion inferred from the macroscopic deformation, evolving from fast diffusivelike dynamics at the onset of swelling to slower, yet supradiffusive, rearrangements at later stages.
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Gao SR, Jia QH, Liu Z, Shi SH, Wang YF, Zheng SF, Yang YR, Hsu SH, Yan WM, Wang XD. Bouncing Dynamics of Drops' Successive Off-Center Impact. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2024; 40:10759-10768. [PMID: 38712734 DOI: 10.1021/acs.langmuir.4c00913] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2024]
Abstract
Bouncing dynamics of a trailing drop off-center impacting a leading drop with varying time intervals and Weber numbers are investigated experimentally. Whether the trailing drop impacts during the spreading or receding process of the leading drop is determined by the time interval. For a short time interval of 0.15 ≤ Δt* ≤ 0.66, the trailing drop impacts during the spreading of the leading drop, and the drops completely coalesce and rebound; for a large time interval of 0.66 < Δt* ≤ 2.21, the trailing drop impacts during the receding process, and the drops partially coalesce and rebound. Whether the trailing drop directly impacts the surface or the liquid film of the leading drop is determined by the Weber number. The trailing drop impacts the surface directly at moderate Weber numbers of 16.22 ≤ We ≤ 45.42, while it impacts the liquid film at large Weber numbers of 45.42 < We ≤ 64.88. Intriguingly, when the trailing drop impacts the surface directly or the receding liquid film, the contact time increases linearly with the time interval but independent of the Weber number; when the trailing drop impacts the spreading liquid film, the contact time suddenly increases, showing that the force of the liquid film of the leading drop inhibits the receding of the trailing drop. Finally, a theoretical model of the contact time for the drops is established, which is suitable for different impact scenarios of the successive off-center impact. This study provides a quantitative relationship to calculate the contact time of drops successively impacting a superhydrophobic surface, facilitating the design of anti-icing surfaces.
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Affiliation(s)
- Shu-Rong Gao
- Research Center of Engineering Thermophysics, North China Electric Power University, Beijing 102206, China
- State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources, North China Electric Power University, Beijing 102206, China
- Key Laboratory of Icing and Anti/De-icing, China Aerodynamics Research and Development Center, Mianyang, Sichuan 621000, China
| | - Qi-Hui Jia
- Research Center of Engineering Thermophysics, North China Electric Power University, Beijing 102206, China
- State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources, North China Electric Power University, Beijing 102206, China
| | - Zhe Liu
- Research Center of Engineering Thermophysics, North China Electric Power University, Beijing 102206, China
- State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources, North China Electric Power University, Beijing 102206, China
| | - Shi-Hua Shi
- Research Center of Engineering Thermophysics, North China Electric Power University, Beijing 102206, China
- State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources, North China Electric Power University, Beijing 102206, China
| | - Yi-Feng Wang
- Research Center of Engineering Thermophysics, North China Electric Power University, Beijing 102206, China
- State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources, North China Electric Power University, Beijing 102206, China
| | - Shao-Fei Zheng
- Research Center of Engineering Thermophysics, North China Electric Power University, Beijing 102206, China
- State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources, North China Electric Power University, Beijing 102206, China
| | - Yan-Ru Yang
- Research Center of Engineering Thermophysics, North China Electric Power University, Beijing 102206, China
- State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources, North China Electric Power University, Beijing 102206, China
| | - Shu-Han Hsu
- Department of Mechanical Engineering, National Taipei University of Technology, Taipei 10608, Taiwan
| | - Wei-Mon Yan
- Department of Mechanical Engineering, National Taipei University of Technology, Taipei 10608, Taiwan
| | - Xiao-Dong Wang
- Research Center of Engineering Thermophysics, North China Electric Power University, Beijing 102206, China
- State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources, North China Electric Power University, Beijing 102206, China
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Charles CA, Louhichi A, Ramos L, Ligoure C. Viscoelasticity and elastocapillarity effects in the impact of drops on a repellent surface. SOFT MATTER 2021; 17:5829-5837. [PMID: 34037061 DOI: 10.1039/d1sm00438g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
We investigate freely expanding viscoelastic sheets. The sheets are produced by the impact of drops on a quartz plate covered with a thin layer of liquid nitrogen that suppresses shear viscous dissipation as a result of the cold Leidenfrost effect. The time evolution of the sheet is simultaneously recorded from top and side views using high-speed cameras. The investigated viscoelastic fluids are Maxwell fluids, which are characterized by low elastic moduli, and relaxation times that vary over almost two orders of magnitude, thus giving access to a large spectrum of viscoelastic and elastocapillary effects. For the purposes of comparison, Newtonian fluids, with viscosity varying over three orders of magnitude, are also investigated. In this study, dmax, the maximal expansion of the sheets, and tmax the time to reach this maximal expansion from the time at impact, are measured as a function of the impact velocity. By using a generalized damped harmonic oscillator model, we rationalize the role of capillarity, bulk elasticity and viscous dissipation in the expansion dynamics of all investigated samples. In the model, the spring constant is a combination of the surface tension and the bulk dynamic elastic modulus. The time-varying damping coefficient is associated to biaxial extensional viscous dissipation and is proportional to the dynamic loss modulus. For all samples, we find that the model reproduces accurately the experimental data for dmax and tmax.
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Affiliation(s)
- Carole-Ann Charles
- Laboratoire Charles Coulomb (L2C), Université de Montpellier, CNRS, Montpellier, France.
| | - Ameur Louhichi
- Laboratoire Charles Coulomb (L2C), Université de Montpellier, CNRS, Montpellier, France.
| | - Laurence Ramos
- Laboratoire Charles Coulomb (L2C), Université de Montpellier, CNRS, Montpellier, France.
| | - Christian Ligoure
- Laboratoire Charles Coulomb (L2C), Université de Montpellier, CNRS, Montpellier, France.
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Carbonaro A, Chagua-Encarnacion KN, Charles CA, Phou T, Ligoure C, Mora S, Truzzolillo D. Spinning elastic beads: a route for simultaneous measurements of the shear modulus and the interfacial energy of soft materials. SOFT MATTER 2020; 16:8412-8421. [PMID: 32808946 DOI: 10.1039/d0sm01024c] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Large deformations of soft elastic beads spinning at high angular velocity in a denser background fluid are investigated theoretically, numerically, and experimentally using millimeter-size polyacrylamide hydrogel particles introduced in a spinning drop tensiometer. We determine the equilibrium shapes of the beads from the competition between the centrifugal force and the restoring elastic and surface forces. Considering the beads as neo-Hookean up to large deformations, we show that their elastic modulus and interfacial energy constant can be simultaneously deduced from their equilibrium shape. Also, our results provide further support to the scenario in which interfacial energy and interfacial tension coincide for amorphous polymer gels.
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Affiliation(s)
- Alessandro Carbonaro
- Laboratoire Charles Coulomb, Université de Montpellier and CNRS, F-34095 Montpellier, France.
| | | | - Carole-Ann Charles
- Laboratoire Charles Coulomb, Université de Montpellier and CNRS, F-34095 Montpellier, France.
| | - Ty Phou
- Laboratoire Charles Coulomb, Université de Montpellier and CNRS, F-34095 Montpellier, France.
| | - Christian Ligoure
- Laboratoire Charles Coulomb, Université de Montpellier and CNRS, F-34095 Montpellier, France.
| | - Serge Mora
- Laboratoire de Mécanique et Génie Civil, Université de Montpellier and CNRS, F-34090 Montpellier, France.
| | - Domenico Truzzolillo
- Laboratoire Charles Coulomb, Université de Montpellier and CNRS, F-34095 Montpellier, France.
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Wang X, Lin D, Wang Y, Gao S, Yang Y, Wang X. Rebound dynamics of two droplets simultaneously impacting a flat superhydrophobic surface. AIChE J 2020. [DOI: 10.1002/aic.16647] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Xin Wang
- Research Center of Engineering ThermophysicsNorth China Electric Power University Beijing China
- State Key Laboratory of Alternate Electrical Power System with Renewable Energy SourcesNorth China Electric Power University Beijing China
| | - Dian‐Ji Lin
- Research Center of Engineering ThermophysicsNorth China Electric Power University Beijing China
- State Key Laboratory of Alternate Electrical Power System with Renewable Energy SourcesNorth China Electric Power University Beijing China
| | - Yi‐Bo Wang
- Research Center of Engineering ThermophysicsNorth China Electric Power University Beijing China
- State Key Laboratory of Alternate Electrical Power System with Renewable Energy SourcesNorth China Electric Power University Beijing China
| | - Shu‐Rong Gao
- Research Center of Engineering ThermophysicsNorth China Electric Power University Beijing China
- State Key Laboratory of Alternate Electrical Power System with Renewable Energy SourcesNorth China Electric Power University Beijing China
| | - Yan‐Ru Yang
- Research Center of Engineering ThermophysicsNorth China Electric Power University Beijing China
- State Key Laboratory of Alternate Electrical Power System with Renewable Energy SourcesNorth China Electric Power University Beijing China
| | - Xiao‐Dong Wang
- Research Center of Engineering ThermophysicsNorth China Electric Power University Beijing China
- State Key Laboratory of Alternate Electrical Power System with Renewable Energy SourcesNorth China Electric Power University Beijing China
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Abstract
We study the bouncing dynamics of nanodroplets on superhydrophobic surfaces. We show that there are three velocity regimes with different scaling laws of the contact time, τ. Although τ remains constant over a wide velocity range, as seen for macroscale bouncing, we demonstrate that viscosity plays an essential role in nanodroplet bouncing even for low-viscosity fluids. We propose a new scaling τ ∼ (ρμR04/γ2)1/3 = (R0/v0)We2/3Re-1/3 to characterize the viscosity effect, which agrees well with the simulated results for water and argon nanodroplets with various radii and hydrophobicities. We also find pancake bouncing of nanodroplets, which is responsible for an abruptly reduced τ in a high-velocity regime.
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Affiliation(s)
- Fang-Fang Xie
- Research Center of Engineering Thermophysics, North China Electric Power University, Beijing 102206, China
- State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources, North China Electric Power University, Beijing 102206, China
| | - Shu-Hang Lv
- Research Center of Engineering Thermophysics, North China Electric Power University, Beijing 102206, China
- State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources, North China Electric Power University, Beijing 102206, China
| | - Yan-Ru Yang
- Research Center of Engineering Thermophysics, North China Electric Power University, Beijing 102206, China
- State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources, North China Electric Power University, Beijing 102206, China
| | - Xiao-Dong Wang
- Research Center of Engineering Thermophysics, North China Electric Power University, Beijing 102206, China
- State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources, North China Electric Power University, Beijing 102206, China
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Mora S, Andò E, Fromental JM, Phou T, Pomeau Y. The shape of hanging elastic cylinders. SOFT MATTER 2019; 15:5464-5473. [PMID: 31232424 DOI: 10.1039/c9sm00625g] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Deformations of heavy elastic cylinders with their axis in the direction of earth's gravity field are investigated. The specimens, made of polyacrylamide hydrogels, are attached from their top circular cross section to a rigid plate. An equilibrium configuration results from the interplay between gravity that tends to deform the cylinders downwards under their own weight, and elasticity that resists these distortions. The corresponding steady state exhibits fascinating shapes which are measured with lab-based micro-tomography. For any given initial radius to height ratio, the deformed cylinders are no longer axially symmetric beyond a critical value of a control parameter that depends on the volume force, the height and the elastic modulus: self-similar wrinkling hierarchies develop, and dimples appear at the bottom surface of the shallowest samples. We show that these patterns are the consequences of elastic instabilities.
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Affiliation(s)
- Serge Mora
- Laboratoire de Mécanique et de Génie Civil, Université de Montpellier and CNRS, 163 rue Auguste Broussonnet, F-34090 Montpellier, France.
| | - Edward Andò
- Laboratoire 3SR, Université Grenoble Alpes and CNRS, F-38041 Grenoble, France
| | - Jean-Marc Fromental
- Laboratoire Charles Coulomb, Université de Montpellier and CNRS, 163 rue Auguste Broussonnet, F-34090 Montpellier, France
| | - Ty Phou
- Laboratoire Charles Coulomb, Université de Montpellier and CNRS, 163 rue Auguste Broussonnet, F-34090 Montpellier, France
| | - Yves Pomeau
- University of Arizona, Department of Mathematics, Tucson, USA
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