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Dolganov PV, Shuravin NS, Dolganov VK, Kats EI, Stannarius R, Harth K, Trittel T, Park CS, Maclennan JE. Transient hexagonal structures in sheared emulsions of isotropic inclusions on smectic bubbles in microgravity conditions. Sci Rep 2021; 11:19144. [PMID: 34580344 PMCID: PMC8476617 DOI: 10.1038/s41598-021-98166-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2021] [Accepted: 08/19/2021] [Indexed: 11/08/2022] Open
Abstract
We describe the collective behavior of isotropic droplets dispersed over a spherical smectic bubble, observed under microgravity conditions on the International Space Station (ISS). We find that droplets can form two-dimensional hexagonal structures changing with time. Our analysis indicates the possibility of spatial and temporal periodicity of such structures of droplets. Quantitative analysis of the hexagonal structure including the first three coordination circles was performed. A peculiar periodic-in-time ordering of the droplets, related to one-dimensional motion of droplets with non-uniform velocity, was found.
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Affiliation(s)
- P V Dolganov
- Institute of Solid State Physics, Russian Academy of Sciences (ISSP RAS), 142432, Chernogolovka, Moscow Region, Russia
| | - N S Shuravin
- Institute of Solid State Physics, Russian Academy of Sciences (ISSP RAS), 142432, Chernogolovka, Moscow Region, Russia
| | - V K Dolganov
- Institute of Solid State Physics, Russian Academy of Sciences (ISSP RAS), 142432, Chernogolovka, Moscow Region, Russia.
| | - E I Kats
- L.D. Landau Institute for Theoretical Physics, Russian Academy of Sciences, 142432, Chernogolovka, Moscow Region, Russia
| | - R Stannarius
- Institute of Physics, Otto von Guericke University, 39106, Magdeburg, Germany
| | - K Harth
- Institute of Physics, Otto von Guericke University, 39106, Magdeburg, Germany
| | - T Trittel
- Institute of Physics, Otto von Guericke University, 39106, Magdeburg, Germany
| | - C S Park
- Department of Physics, University of Colorado Boulder, Boulder, CO, 80309, USA
| | - J E Maclennan
- Department of Physics, University of Colorado Boulder, Boulder, CO, 80309, USA
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Abstract
We demonstrate controlled material transport driven by temperature differences in thin freely suspended smectic films. Films with submicrometer thicknesses and lateral extensions of several millimeters were studied in microgravity during suborbital rocket flights. In-plane temperature differences cause two specific Marangoni effects, directed flow and convection patterns. At low gradients, practically thresholdless, flow transports material with a normal (negative) temperature coefficient of the surface tension dσ/dT<0 from the hot to the cold film edge, it accumulates at the cold film edge. In materials with dσ/dT>0, the reverse transport from the cold to the hot edge is observed. We present a model that describes the effect quantitatively. It predicts that not the temperature gradient in the film plane but the temperature difference between the thermopads is relevant for the effect.
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Affiliation(s)
- T Trittel
- Institute of Experimental Physics, Otto von Guericke University, 39106 Magdeburg, Germany
| | - K Harth
- Institute of Experimental Physics, Otto von Guericke University, 39106 Magdeburg, Germany
- Universiteit Twente, Physics of Fluids and Max Planck Center for Complex Fluid Dynamics, P.O. Box 217, 7500 AE Enschede, Netherlands
| | - C Klopp
- Institute of Experimental Physics, Otto von Guericke University, 39106 Magdeburg, Germany
| | - R Stannarius
- Institute of Experimental Physics, Otto von Guericke University, 39106 Magdeburg, Germany
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Ashour A, Wegner S, Trittel T, Börzsönyi T, Stannarius R. Outflow and clogging of shape-anisotropic grains in hoppers with small apertures. Soft Matter 2017; 13:402-414. [PMID: 27878164 DOI: 10.1039/c6sm02374f] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Outflow of granular material through a small orifice is a fundamental process in many industrial fields, for example in silo discharge, and in everyday's life. Most experimental studies of the dynamics have been performed so far with monodisperse disks in two-dimensional (2D) hoppers or spherical grains in 3D. We investigate this process for shape-anisotropic grains in 3D hoppers and discuss the role of size and shape parameters on avalanche statistics, clogging states, and mean flow velocities. It is shown that an increasing aspect ratio of the grains leads to lower flow rates and higher clogging probabilities compared to spherical grains. On the other hand, the number of grains forming the clog is larger for elongated grains of comparable volumes, and the long axis of these blocking grains is preferentially aligned towards the center of the orifice. We find a qualitative transition in the hopper discharge behavior for aspect ratios larger than ≈6. At still higher aspect ratios >8-12, the outflowing material leaves long vertical holes in the hopper that penetrate the complete granular bed. This changes the discharge characteristics qualitatively.
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Affiliation(s)
- A Ashour
- Institute of Experimental Physics, Otto von Guericke University, 39106 Magdeburg, Germany. and Faculty of Engineering and Technology, Future University, End of 90 St., New Cairo, Egypt
| | - S Wegner
- Institute of Experimental Physics, Otto von Guericke University, 39106 Magdeburg, Germany.
| | - T Trittel
- Institute of Experimental Physics, Otto von Guericke University, 39106 Magdeburg, Germany.
| | - T Börzsönyi
- Institute for Solid State Physics and Optics, Wigner Research Center for Physics, Hungarian Academy of Sciences, P. O. Box 49, H-1525 Budapest, Hungary
| | - R Stannarius
- Institute of Experimental Physics, Otto von Guericke University, 39106 Magdeburg, Germany.
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Harth K, Kornek U, Trittel T, Strachauer U, Höme S, Will K, Stannarius R. Granular gases of rod-shaped grains in microgravity. Phys Rev Lett 2013; 110:144102. [PMID: 25166993 DOI: 10.1103/physrevlett.110.144102] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/17/2012] [Indexed: 06/03/2023]
Abstract
Granular gases are convenient model systems to investigate the statistical physics of nonequilibrium systems. In the literature, one finds numerous theoretical predictions, but only few experiments. We study a weakly excited dilute gas of rods, confined in a cuboid container in microgravity during a suborbital rocket flight. With respect to a gas of spherical grains at comparable filling fraction, the mean free path is considerably reduced. This guarantees a dominance of grain-grain collisions over grain-wall collisions. No clustering was observed, unlike in similar experiments with spherical grains. Rod positions and orientations were determined and tracked. Translational and rotational velocity distributions are non-Gaussian. Equipartition of kinetic energy between translations and rotations is violated.
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Affiliation(s)
- K Harth
- Institute of Experimental Physics, Otto-von-Guericke Universität Magdeburg, D-39016 Magdeburg, Germany
| | - U Kornek
- Institute of Experimental Physics, Otto-von-Guericke Universität Magdeburg, D-39016 Magdeburg, Germany
| | - T Trittel
- Institute of Experimental Physics, Otto-von-Guericke Universität Magdeburg, D-39016 Magdeburg, Germany
| | - U Strachauer
- Institute of Experimental Physics, Otto-von-Guericke Universität Magdeburg, D-39016 Magdeburg, Germany
| | - S Höme
- Institute of Automation Engineering, Otto-von-Guericke Universität Magdeburg, D-39016 Magdeburg, Germany
| | - K Will
- Institute for Electronics, Signal Processing and Communications, Otto-von-Guericke Universität Magdeburg, D-39016 Magdeburg, Germany
| | - R Stannarius
- Institute of Experimental Physics, Otto-von-Guericke Universität Magdeburg, D-39016 Magdeburg, Germany
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Morys M, Trittel T, Eremin A, Murphy P, Stannarius R. Tension of freely suspended fluid filaments. Phys Rev E Stat Nonlin Soft Matter Phys 2012; 86:040501. [PMID: 23214519 DOI: 10.1103/physreve.86.040501] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/02/2012] [Indexed: 06/01/2023]
Abstract
Stable fluid filaments with diameters of several micrometers and slenderness ratios well above 1000 are unique objects formed by some liquid crystalline phases of bent-core mesogens. We present a technique to determine filament tensions from their deflection under defined loads. A strong temperature dependence is observed, with a minimum near the clearing temperature. Both the nonlinear relation between filament tension and diameter and the substantial increase of the tension with lower temperatures indicate contributions of volume terms, in addition to surface capillary forces. We discuss a model that relates these bulk terms to elastic forces, originating from the undulated smectic layer structure. This model can explain the origin of the filament stability.
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Affiliation(s)
- M Morys
- Otto von Guericke University Magdeburg, Institute of Experimental Physics, Universitätsplatz 2, D-39106 Magdeburg, Germany
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