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Lyu S, Mathai V, Wang Y, Sobac B, Colinet P, Lohse D, Sun C. Final fate of a Leidenfrost droplet: Explosion or takeoff. SCIENCE ADVANCES 2019; 5:eaav8081. [PMID: 31058224 PMCID: PMC6499590 DOI: 10.1126/sciadv.aav8081] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2018] [Accepted: 03/15/2019] [Indexed: 06/02/2023]
Abstract
When a liquid droplet is placed on a very hot solid, it levitates on its own vapor layer, a phenomenon called the Leidenfrost effect. Although the mechanisms governing the droplet's levitation have been explored, not much is known about the fate of the Leidenfrost droplet. Here we report on the final stages of evaporation of Leidenfrost droplets. While initially small droplets tend to take off, unexpectedly, the initially large ones explode with a crack sound. We interpret these in the context of unavoidable droplet contaminants, which accumulate at the droplet-air interface, resulting in reduced evaporation rate, and contact with the substrate. We validate this hypothesis by introducing controlled amounts of microparticles and reveal a universal 1/3-scaling law for the dimensionless explosion radius versus contaminant fraction. Our findings open up new opportunities for controlling the duration and rate of Leidenfrost heat transfer and propulsion by tuning the droplet's size and contamination.
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Affiliation(s)
- Sijia Lyu
- Center for Combustion Energy, Key Laboratory for Thermal Science and Power Engineering of Ministry of Education, Department of Energy and Power Engineering, Tsinghua University, 100084 Beijing, China
| | - Varghese Mathai
- School of Engineering, Brown University, Providence, RI 02912, USA
| | - Yujie Wang
- Center for Combustion Energy, Key Laboratory for Thermal Science and Power Engineering of Ministry of Education, Department of Energy and Power Engineering, Tsinghua University, 100084 Beijing, China
| | - Benjamin Sobac
- Université libre de Bruxelles, TIPs-Fluid Physics, 1050 Brussels, Belgium
| | - Pierre Colinet
- Université libre de Bruxelles, TIPs-Fluid Physics, 1050 Brussels, Belgium
| | - Detlef Lohse
- Center for Combustion Energy, Key Laboratory for Thermal Science and Power Engineering of Ministry of Education, Department of Energy and Power Engineering, Tsinghua University, 100084 Beijing, China
- Physics of Fluids Group and Max Planck Center Twente for Complex Fluid Dynamics, University of Twente, Enschede, Netherlands
| | - Chao Sun
- Center for Combustion Energy, Key Laboratory for Thermal Science and Power Engineering of Ministry of Education, Department of Energy and Power Engineering, Tsinghua University, 100084 Beijing, China
- Physics of Fluids Group and Max Planck Center Twente for Complex Fluid Dynamics, University of Twente, Enschede, Netherlands
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Mathai V, Huisman SG, Sun C, Lohse D, Bourgoin M. Dispersion of Air Bubbles in Isotropic Turbulence. PHYSICAL REVIEW LETTERS 2018; 121:054501. [PMID: 30118276 DOI: 10.1103/physrevlett.121.054501] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/16/2018] [Indexed: 06/08/2023]
Abstract
Bubbles play an important role in the transport of chemicals and nutrients in many natural and industrial flows. Their dispersion is crucial to understanding the mixing processes in these flows. Here we report on the dispersion of millimetric air bubbles in a homogeneous and isotropic turbulent flow with a Taylor Reynolds number from 110 to 310. We find that the mean squared displacement (MSD) of the bubbles far exceeds that of fluid tracers in turbulence. The MSD shows two regimes. At short times, it grows ballistically (∝τ^{2}), while at larger times, it approaches the diffusive regime where the MSD∝τ. Strikingly, for the bubbles, the ballistic-to-diffusive transition occurs one decade earlier than for the fluid. We reveal that both the enhanced dispersion and the early transition to the diffusive regime can be traced back to the unsteady wake-induced motion of the bubbles. Further, the diffusion transition for bubbles is not set by the integral timescale of the turbulence (as it is for fluid tracers and microbubbles), but instead, by a timescale of eddy crossing of the rising bubbles. The present findings provide a Lagrangian perspective towards understanding mixing in turbulent bubbly flows.
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Affiliation(s)
- Varghese Mathai
- Physics of Fluids Group, Department of Science and Technology, Max Planck Center Twente for Complex Fluid Dynamics, MESA+Institute, and J. M. Burgers Center for Fluid Dynamics, University of Twente, P.O. Box 217, 7500 AE Enschede, Netherlands
| | - Sander G Huisman
- Physics of Fluids Group, Department of Science and Technology, Max Planck Center Twente for Complex Fluid Dynamics, MESA+Institute, and J. M. Burgers Center for Fluid Dynamics, University of Twente, P.O. Box 217, 7500 AE Enschede, Netherlands
- Université Lyon, ENS de Lyon, Université Claude Bernard, CNRS, Laboratoire de Physique, F-69342 Lyon, France
| | - Chao Sun
- Physics of Fluids Group, Department of Science and Technology, Max Planck Center Twente for Complex Fluid Dynamics, MESA+Institute, and J. M. Burgers Center for Fluid Dynamics, University of Twente, P.O. Box 217, 7500 AE Enschede, Netherlands
- Center for Combustion Energy, Key Laboratory for Thermal Science and Power Engineering of Ministry of Education, Department of Energy and Power Engineering, Tsinghua University, 100084 Beijing, China
| | - Detlef Lohse
- Physics of Fluids Group, Department of Science and Technology, Max Planck Center Twente for Complex Fluid Dynamics, MESA+Institute, and J. M. Burgers Center for Fluid Dynamics, University of Twente, P.O. Box 217, 7500 AE Enschede, Netherlands
- Max Planck Institute for Dynamics and Self-Organization, 37077 Göttingen, Germany
| | - Mickaël Bourgoin
- Université Lyon, ENS de Lyon, Université Claude Bernard, CNRS, Laboratoire de Physique, F-69342 Lyon, France
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Mathai V, Zhu X, Sun C, Lohse D. Flutter to tumble transition of buoyant spheres triggered by rotational inertia changes. Nat Commun 2018; 9:1792. [PMID: 29728557 PMCID: PMC5935758 DOI: 10.1038/s41467-018-04177-w] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2017] [Accepted: 04/08/2018] [Indexed: 11/12/2022] Open
Abstract
Heavy particles sink straight in water, while buoyant bubbles and spheres may zigzag or spiral as they rise. The precise conditions that trigger such path-instabilities are still not completely understood. For a buoyant rising sphere, two parameters are believed to govern the development of unsteady dynamics: the particle's density relative to the fluid, and its Galileo number. Consequently, with these parameters specified, the opportunities for variation in particle dynamics appear limited. In contrast to this picture, here we demonstrate that vigorous path-oscillations can be triggered by modulating a spherical particle's moment of inertia (MoI). For a buoyant sphere rising in a turbulent flow, MoI reduction triggers a tumble-flutter transition, while in quiescent liquid, it induces a modification of the sphere wake resulting in large-amplitude path-oscillations. The present finding opens the door for control of particle path- and wake-instabilities, with potential for enhanced mixing and heat transfer in particle-laden and dispersed multiphase environments.
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Affiliation(s)
- Varghese Mathai
- Physics of Fluids Group and Max Planck Center for Complex Fluid Dynamics, MESA+ Institute and J. M. Burgers Centre for Fluid Dynamics, University of Twente, P.O. Box 217, 7500AE, Enschede, The Netherlands
| | - Xiaojue Zhu
- Physics of Fluids Group and Max Planck Center for Complex Fluid Dynamics, MESA+ Institute and J. M. Burgers Centre for Fluid Dynamics, University of Twente, P.O. Box 217, 7500AE, Enschede, The Netherlands
| | - Chao Sun
- Physics of Fluids Group and Max Planck Center for Complex Fluid Dynamics, MESA+ Institute and J. M. Burgers Centre for Fluid Dynamics, University of Twente, P.O. Box 217, 7500AE, Enschede, The Netherlands.
- Center for Combustion Energy and the Department of Energy and Power Engineering, Tsinghua University, 100084, Beijing, China.
| | - Detlef Lohse
- Physics of Fluids Group and Max Planck Center for Complex Fluid Dynamics, MESA+ Institute and J. M. Burgers Centre for Fluid Dynamics, University of Twente, P.O. Box 217, 7500AE, Enschede, The Netherlands.
- Center for Combustion Energy and the Department of Energy and Power Engineering, Tsinghua University, 100084, Beijing, China.
- Max Planck Institute for Dynamics and Self-Organization, 37077, Göttingen, Germany.
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Gustavsson K, Jucha J, Naso A, Lévêque E, Pumir A, Mehlig B. Statistical Model for the Orientation of Nonspherical Particles Settling in Turbulence. PHYSICAL REVIEW LETTERS 2017; 119:254501. [PMID: 29303314 DOI: 10.1103/physrevlett.119.254501] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2017] [Indexed: 06/07/2023]
Abstract
The orientation of small anisotropic particles settling in a turbulent fluid determines some essential properties of the suspension. We show that the orientation distribution of small heavy spheroids settling through turbulence can be accurately predicted by a simple Gaussian statistical model that takes into account particle inertia and provides a quantitative understanding of the orientation distribution on the problem parameters when fluid inertia is negligible. Our results open the way to a parametrization of the distribution of ice crystals in clouds, and potentially lead to an improved understanding of radiation reflection or particle aggregation through collisions in clouds.
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Affiliation(s)
- K Gustavsson
- Department of Physics, Gothenburg University, 41296 Gothenburg, Sweden
| | - J Jucha
- Laboratoire de Physique, Ecole Normale Supérieure de Lyon and CNRS, F-69007 Lyon, France
- Projektträger Jülich, Forschungszentrum Jülich GmbH, D-52425 Jülich, Germany
| | - A Naso
- LMFA, Ecole Centrale de Lyon and CNRS, F-69134 Ecully, France
| | - E Lévêque
- LMFA, Ecole Centrale de Lyon and CNRS, F-69134 Ecully, France
| | - A Pumir
- Laboratoire de Physique, Ecole Normale Supérieure de Lyon and CNRS, F-69007 Lyon, France
| | - B Mehlig
- Department of Physics, Gothenburg University, 41296 Gothenburg, Sweden
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Mathai V, Zhu X, Sun C, Lohse D. Mass and Moment of Inertia Govern the Transition in the Dynamics and Wakes of Freely Rising and Falling Cylinders. PHYSICAL REVIEW LETTERS 2017; 119:054501. [PMID: 28949731 DOI: 10.1103/physrevlett.119.054501] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2017] [Indexed: 06/07/2023]
Abstract
In this Letter, we study the motion and wake patterns of freely rising and falling cylinders in quiescent fluid. We show that the amplitude of oscillation and the overall system dynamics are intricately linked to two parameters: the particle's mass density relative to the fluid m^{*}≡ρ_{p}/ρ_{f} and its relative moment of inertia I^{*}≡I_{p}/I_{f}. This supersedes the current understanding that a critical mass density (m^{*}≈0.54) alone triggers the sudden onset of vigorous vibrations. Using over 144 combinations of m^{*} and I^{*}, we comprehensively map out the parameter space covering very heavy (m^{*}>10) to very buoyant (m^{*}<0.1) particles. The entire data collapse into two scaling regimes demarcated by a transitional Strouhal number St_{t}≈0.17. St_{t} separates a mass-dominated regime from a regime dominated by the particle's moment of inertia. A shift from one regime to the other also marks a gradual transition in the wake-shedding pattern: from the classical two-single (2S) vortex mode to a two-pair (2P) vortex mode. Thus, autorotation can have a significant influence on the trajectories and wakes of freely rising isotropic bodies.
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Affiliation(s)
- Varghese Mathai
- Physics of Fluids Group and Max Planck Center Twente, J. M. Burgers Centre for Fluid Dynamics, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands
| | - Xiaojue Zhu
- Physics of Fluids Group and Max Planck Center Twente, J. M. Burgers Centre for Fluid Dynamics, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands
| | - Chao Sun
- Physics of Fluids Group and Max Planck Center Twente, J. M. Burgers Centre for Fluid Dynamics, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands
- Center for Combustion Energy and Department of Thermal Engineering, Tsinghua University, 100084 Beijing, China
| | - Detlef Lohse
- Physics of Fluids Group and Max Planck Center Twente, J. M. Burgers Centre for Fluid Dynamics, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands
- Max Planck Institute for Dynamics and Self-Organization, 37077 Göttingen, Germany
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Candelier F, Einarsson J, Mehlig B. Angular Dynamics of a Small Particle in Turbulence. PHYSICAL REVIEW LETTERS 2016; 117:204501. [PMID: 27886512 DOI: 10.1103/physrevlett.117.204501] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2016] [Indexed: 06/06/2023]
Abstract
We compute the angular dynamics of a neutrally buoyant nearly spherical particle immersed in an unsteady fluid. We assume that the particle is small, that its translational slip velocity is negligible, and that unsteady and convective inertia are small perturbations. We derive an approximation for the torque on the particle that determines the first inertial corrections to Jeffery's equation. These corrections arise as a consequence of local vortex stretching and can be substantial in turbulence, where local vortex stretching is strong and closely linked to the irreversibility of turbulence.
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Affiliation(s)
- F Candelier
- Aix-Marseille University-IUSTI (UMR CNRS 7343), 13 453 Marseille Cedex, France
| | - J Einarsson
- Department of Physics, Gothenburg University, SE-41296 Gothenburg, Sweden
| | - B Mehlig
- Department of Physics, Gothenburg University, SE-41296 Gothenburg, Sweden
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Tan H, Peng S, Sun C, Zhang X, Lohse D. 3D spherical-cap fitting procedure for (truncated) sessile nano- and micro-droplets & -bubbles. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2016; 39:106. [PMID: 27841013 DOI: 10.1140/epje/i2016-16106-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2016] [Accepted: 10/14/2016] [Indexed: 05/25/2023]
Abstract
In the study of nanobubbles, nanodroplets or nanolenses immobilised on a substrate, a cross-section of a spherical cap is widely applied to extract geometrical information from atomic force microscopy (AFM) topographic images. In this paper, we have developed a comprehensive 3D spherical-cap fitting procedure (3D-SCFP) to extract morphologic characteristics of complete or truncated spherical caps from AFM images. Our procedure integrates several advanced digital image analysis techniques to construct a 3D spherical-cap model, from which the geometrical parameters of the nanostructures are extracted automatically by a simple algorithm. The procedure takes into account all valid data points in the construction of the 3D spherical-cap model to achieve high fidelity in morphology analysis. We compare our 3D fitting procedure with the commonly used 2D cross-sectional profile fitting method to determine the contact angle of a complete spherical cap and a truncated spherical cap. The results from 3D-SCFP are consistent and accurate, while 2D fitting is unavoidably arbitrary in the selection of the cross-section and has a much lower number of data points on which the fitting can be based, which in addition is biased to the top of the spherical cap. We expect that the developed 3D spherical-cap fitting procedure will find many applications in imaging analysis.
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Affiliation(s)
- Huanshu Tan
- Physics of Fluids group, Department of Science and Technology, Mesa+ Institute, and J. M. Burgers Centre for Fluid Dynamics, University of Twente, P.O. Box 217, 7500, AE Enschede, The Netherlands.
| | - Shuhua Peng
- Soft Matter & Interfaces Group, School of Engineering, RMIT University, VIC 3001, Melbourne, Australia
| | - Chao Sun
- Physics of Fluids group, Department of Science and Technology, Mesa+ Institute, and J. M. Burgers Centre for Fluid Dynamics, University of Twente, P.O. Box 217, 7500, AE Enschede, The Netherlands
- Center for Combustion Energy & Department of Thermal Engineering, Tsinghua University, Beijing, China
| | - Xuehua Zhang
- Physics of Fluids group, Department of Science and Technology, Mesa+ Institute, and J. M. Burgers Centre for Fluid Dynamics, University of Twente, P.O. Box 217, 7500, AE Enschede, The Netherlands
- Soft Matter & Interfaces Group, School of Engineering, RMIT University, VIC 3001, Melbourne, Australia
| | - Detlef Lohse
- Physics of Fluids group, Department of Science and Technology, Mesa+ Institute, and J. M. Burgers Centre for Fluid Dynamics, University of Twente, P.O. Box 217, 7500, AE Enschede, The Netherlands
- Max Planck Institute for Dynamics and Self-Organization, 37077, Göttingen, Germany
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Mathai V, Calzavarini E, Brons J, Sun C, Lohse D. Microbubbles and Microparticles are Not Faithful Tracers of Turbulent Acceleration. PHYSICAL REVIEW LETTERS 2016; 117:024501. [PMID: 27447509 DOI: 10.1103/physrevlett.117.024501] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/16/2016] [Indexed: 06/06/2023]
Abstract
We report on the Lagrangian statistics of acceleration of small (sub-Kolmogorov) bubbles and tracer particles with Stokes number St≪1 in turbulent flow. At a decreasing Reynolds number, the bubble accelerations show deviations from that of tracer particles; i.e., they deviate from the Heisenberg-Yaglom prediction and show a quicker decorrelation despite their small size and minute St. Using direct numerical simulations, we show that these effects arise due the drift of these particles through the turbulent flow. We theoretically predict this gravity-driven effect for developed isotropic turbulence, with the ratio of Stokes to Froude number or equivalently the particle drift velocity governing the enhancement of acceleration variance and the reductions in correlation time and intermittency. Our predictions are in good agreement with experimental and numerical results. The present findings are relevant to a range of scenarios encompassing tiny bubbles and droplets that drift through the turbulent oceans and the atmosphere. They also question the common usage of microbubbles and microdroplets as tracers in turbulence research.
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Affiliation(s)
- Varghese Mathai
- Physics of Fluids Group, Faculty of Science and Technology, J. M. Burgers Centre for Fluid Dynamics, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands
| | - Enrico Calzavarini
- Université de Lille, CNRS, FRE 3723, LML, Laboratoire de Mécanique de Lille, F 59000 Lille, France
| | - Jon Brons
- Physics of Fluids Group, Faculty of Science and Technology, J. M. Burgers Centre for Fluid Dynamics, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands
- Applied Mathematics Research Centre, Faculty of Engineering and Computing, Coventry University, Priory Street, Coventry CV1 5FB, United Kingdom
| | - Chao Sun
- Physics of Fluids Group, Faculty of Science and Technology, J. M. Burgers Centre for Fluid Dynamics, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands
- Center for Combustion Energy and Department of Thermal Engineering, Tsinghua University, 100084 Beijing, China
| | - Detlef Lohse
- Physics of Fluids Group, Faculty of Science and Technology, J. M. Burgers Centre for Fluid Dynamics, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands
- Max Planck Institute for Dynamics and Self-Organization, 37077 Göttingen, Germany
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