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Lim MX, VanSaders B, Jaeger HM. Acoustic manipulation of multi-body structures and dynamics. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2024; 87:064601. [PMID: 38670083 DOI: 10.1088/1361-6633/ad43f9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2023] [Accepted: 04/26/2024] [Indexed: 04/28/2024]
Abstract
Sound can exert forces on objects of any material and shape. This has made the contactless manipulation of objects by intense ultrasound a fascinating area of research with wide-ranging applications. While much is understood for acoustic forcing of individual objects, sound-mediated interactions among multiple objects at close range gives rise to a rich set of structures and dynamics that are less explored and have been emerging as a frontier for research. We introduce the basic mechanisms giving rise to sound-mediated interactions among rigid as well as deformable particles, focusing on the regime where the particles' size and spacing are much smaller than the sound wavelength. The interplay of secondary acoustic scattering, Bjerknes forces, and micro-streaming is discussed and the role of particle shape is highlighted. Furthermore, we present recent advances in characterizing non-conservative and non-pairwise additive contributions to the particle interactions, along with instabilities and active fluctuations. These excitations emerge at sufficiently strong sound energy density and can act as an effective temperature in otherwise athermal systems.
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Affiliation(s)
- Melody X Lim
- James Franck Institute, The University of Chicago, Chicago, IL 60637, United States of America
- Department of Physics, The University of Chicago, Chicago, IL 60637, United States of America
| | - Bryan VanSaders
- James Franck Institute, The University of Chicago, Chicago, IL 60637, United States of America
| | - Heinrich M Jaeger
- James Franck Institute, The University of Chicago, Chicago, IL 60637, United States of America
- Department of Physics, The University of Chicago, Chicago, IL 60637, United States of America
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Scase MM, Baldwin KA, Hill RJA. Magnetically induced Rayleigh-Taylor instability under rotation: Comparison of experimental and theoretical results. Phys Rev E 2020; 102:043101. [PMID: 33212718 DOI: 10.1103/physreve.102.043101] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2019] [Accepted: 03/31/2020] [Indexed: 11/07/2022]
Abstract
Our theoretical work has shown that rotating a Rayleigh-Taylor-unstable two-layer stratification about a vertical axis slows the development of the instability under gravity and can stabilize axisymmetric modes indefinitely. Here we compare theoretical predictions directly with our experiments on a rotating two-layer system which is made unstable by magnetic forces applied using a superconducting magnet.
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Affiliation(s)
- M M Scase
- School of Mathematical Sciences, University of Nottingham, Nottingham NG7 2RD, United Kingdom
| | - K A Baldwin
- School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD, United Kingdom.,School of Science and Technology, Nottingham Trent University, Nottingham NG11 8NS, United Kingdom
| | - R J A Hill
- School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD, United Kingdom
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Baldwin KA, de Fouchier JB, Atkinson PS, Hill RJA, Swift MR, Fairhurst DJ. Magnetic Levitation Stabilized by Streaming Fluid Flows. PHYSICAL REVIEW LETTERS 2018; 121:064502. [PMID: 30141657 DOI: 10.1103/physrevlett.121.064502] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2018] [Revised: 05/22/2018] [Indexed: 06/08/2023]
Abstract
We demonstrate that the ubiquitous laboratory magnetic stirrer provides a simple passive method of magnetic levitation, in which the so-called "flea" levitates indefinitely. We study the onset of levitation and quantify the flea's motion (a combination of vertical oscillation, spinning and "waggling"), finding excellent agreement with a mechanical analytical model. The waggling motion drives recirculating flow, producing a centripetal reaction force that stabilized the flea. Our findings have implications for the locomotion of artificial swimmers and the development of bidirectional microfluidic pumps, and they provide an alternative to sophisticated commercial levitators.
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Affiliation(s)
- K A Baldwin
- Max Planck Institute for Dynamics and Self-Organization, 37077 Göttingen, Germany
- School of Science and Technology, Nottingham Trent University, Nottingham NG11 8NS, United Kingdom
| | - J-B de Fouchier
- School of Science and Technology, Nottingham Trent University, Nottingham NG11 8NS, United Kingdom
| | - P S Atkinson
- School of Science and Technology, Nottingham Trent University, Nottingham NG11 8NS, United Kingdom
| | - R J A Hill
- School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD, United Kingdom
| | - M R Swift
- School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD, United Kingdom
| | - D J Fairhurst
- School of Science and Technology, Nottingham Trent University, Nottingham NG11 8NS, United Kingdom
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Klotsa D, Baldwin KA, Hill RJA, Bowley RM, Swift MR. Propulsion of a Two-Sphere Swimmer. PHYSICAL REVIEW LETTERS 2015; 115:248102. [PMID: 26705658 DOI: 10.1103/physrevlett.115.248102] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/13/2014] [Indexed: 06/05/2023]
Abstract
We describe experiments and simulations demonstrating the propulsion of a neutrally buoyant swimmer that consists of a pair of spheres attached by a spring, immersed in a vibrating fluid. The vibration of the fluid induces relative motion of the spheres which, for sufficiently large amplitudes, can lead to motion of the center of mass of the two spheres. We find that the swimming speed obtained from both experiment and simulation agree and collapse onto a single curve if plotted as a function of the streaming Reynolds number, suggesting that the propulsion is related to streaming flows. There appears to be a critical onset value of the streaming Reynolds number for swimming to occur. We observe a change in the streaming flows as the Reynolds number increases, from that generated by two independent oscillating spheres to a collective flow pattern around the swimmer as a whole. The mechanism for swimming is traced to a strengthening of a jet of fluid in the wake of the swimmer.
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Affiliation(s)
- Daphne Klotsa
- School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD, United Kingdom
- Department of Chemistry, Lensfield Road, University of Cambridge, Cambridge CB2 1EW, United Kingdom
- Department of Applied Physical Sciences, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, USA
| | - Kyle A Baldwin
- School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD, United Kingdom
| | - Richard J A Hill
- School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD, United Kingdom
| | - R M Bowley
- School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD, United Kingdom
| | - Michael R Swift
- School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD, United Kingdom
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The Inhibition of the Rayleigh-Taylor Instability by Rotation. Sci Rep 2015; 5:11706. [PMID: 26130005 PMCID: PMC4486928 DOI: 10.1038/srep11706] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2015] [Accepted: 05/29/2015] [Indexed: 11/08/2022] Open
Abstract
It is well-established that the Coriolis force that acts on fluid in a rotating system can act to stabilise otherwise unstable flows. Chandrasekhar considered theoretically the effect of the Coriolis force on the Rayleigh-Taylor instability, which occurs at the interface between a dense fluid lying on top of a lighter fluid under gravity, concluding that rotation alone could not stabilise this system indefinitely. Recent numerical work suggests that rotation may, nevertheless, slow the growth of the instability. Experimental verification of these results using standard techniques is problematic, owing to the practical difficulty in establishing the initial conditions. Here, we present a new experimental technique for studying the Rayleigh-Taylor instability under rotation that side-steps the problems encountered with standard techniques by using a strong magnetic field to destabilize an otherwise stable system. We find that rotation about an axis normal to the interface acts to retard the growth rate of the instability and stabilise long wavelength modes; the scale of the observed structures decreases with increasing rotation rate, asymptoting to a minimum wavelength controlled by viscosity. We present a critical rotation rate, dependent on Atwood number and the aspect ratio of the system, for stabilising the most unstable mode.
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Hennek JW, Nemiroski A, Subramaniam AB, Bwambok DK, Yang D, Harburg DV, Tricard S, Ellerbee AK, Whitesides GM. Using magnetic levitation for non-destructive quality control of plastic parts. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2015; 27:1587-1592. [PMID: 25589230 DOI: 10.1002/adma.201405207] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/13/2014] [Revised: 12/18/2014] [Indexed: 06/04/2023]
Abstract
Magnetic levitation (MagLev) enables rapid and non-destructive quality control of plastic parts. The feasibility of MagLev as a method to: i) rapidly assess injection-molded plastic parts for defects during process optimization, ii) monitor the degradation of plastics after exposure to harsh environmental conditions, and iii) detect counterfeit polymers by density is demonstrated.
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Affiliation(s)
- Jonathan W Hennek
- Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford St., Cambridge, MA, 02138, USA
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Wang J, Liu C, Ma D. Experimental study of transport of a dimer on a vertically oscillating plate. Proc Math Phys Eng Sci 2014; 470:20140439. [PMID: 25383029 DOI: 10.1098/rspa.2014.0439] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2014] [Accepted: 08/21/2014] [Indexed: 11/12/2022] Open
Abstract
It has recently been shown that a dimer, composed of two identical spheres rigidly connected by a rod, under harmonic vertical vibration can exhibit a self-ordered transport behaviour. In this case, the mass centre of the dimer will perform a circular orbit in the horizontal plane, or a straight line if confined between parallel walls. In order to validate the numerical discoveries, we experimentally investigate the temporal evolution of the dimer's motion in both two- and three-dimensional situations. A stereoscopic vision method with a pair of high-speed cameras is adopted to perform omnidirectional measurements. All the cases studied in our experiments are also simulated using an existing numerical model. The combined investigations detail the dimer's dynamics and clearly show that its transport behaviours originate from a series of combinations of different contact states. This series is critical to our understanding of the transport properties in the dimer's motion and related self-ordered phenomena in granular systems.
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Affiliation(s)
- Jiao Wang
- State Key Laboratory for Turbulence and Complex Systems , College of Engineering, Peking University , Beijing 100871, People's Republic of China
| | - Caishan Liu
- State Key Laboratory for Turbulence and Complex Systems , College of Engineering, Peking University , Beijing 100871, People's Republic of China
| | - Daolin Ma
- State Key Laboratory for Turbulence and Complex Systems , College of Engineering, Peking University , Beijing 100871, People's Republic of China
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