scholarly journals Confinement of surface spinners in liquid metamaterials

2019 ◽  
Vol 116 (51) ◽  
pp. 25424-25429 ◽  
Author(s):  
Jean-Baptiste Gorce ◽  
Hua Xia ◽  
Nicolas Francois ◽  
Horst Punzmann ◽  
Gregory Falkovich ◽  
...  
Keyword(s):  
Self Assembly ◽  
Wave Amplitude ◽  
Optical Lattices ◽  
Standing Waves ◽  
Adjacent Cell ◽  
Nonuniform Flow ◽  
Surface Flows ◽  
Half Wavelength ◽  
Unit Cells ◽  
Generate Surface

We show that rotating particles at the liquid–gas interface can be efficiently manipulated using the surface-wave analogue of optical lattices. Two orthogonal standing waves generate surface flows of counter-rotating half-wavelength unit cells, the liquid interface metamaterial, whose geometry is controlled by the wave phase shift. Here we demonstrate that by placing active magnetic spinners inside such metamaterials, one makes a powerful tool which allows manipulation and self-assembly of spinners, turning them into vehicles capable of transporting matter and information between autonomous metamaterial unit cells. We discuss forces acting on a spinner carried by a nonuniform flow and show how the forces confine spinners to orbit inside the same-sign vortex cells of the wave-driven flow. Reversing the spin, we move the spinner into an adjacent cell. By changing the spinning frequency or the wave amplitude, one can precisely control the spinner orbit. Multiple spinners within a unit cell self-organize into stable patterns, e.g., triangles or squares, orbiting around the center of the cell. Spinners having different frequencies can also be confined, such that the higher-frequency spinner occupies the inner orbit and the lower-frequency one circles on the outer orbit, while the orbital motions of both spinners are synchronized.

scholarly journals Non-reciprocal robotic metamaterials

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Martin Brandenbourger ◽  
Xander Locsin ◽  
Edan Lerner ◽  
Corentin Coulais
Keyword(s):  
Skin Effect ◽  
Mechanical Energy ◽  
Standing Waves ◽  
Control Loops ◽  
Active Metamaterials ◽  
Mechanical Metamaterials ◽  
Wide Range ◽  
Propagating Waves ◽  
Mechanical Analogue ◽  
Unit Cells

Abstract Non-reciprocal transmission of motion is potentially highly beneficial to a wide range of applications, ranging from wave guiding to shock and vibration damping and energy harvesting. To date, large levels of non-reciprocity have been realized using broken spatial or temporal symmetries, yet mostly in the vicinity of resonances, bandgaps or using nonlinearities, thereby non-reciprocal transmission remains limited to narrow ranges of frequencies or input magnitudes and sensitive to attenuation. Here, we create a robotic mechanical metamaterials wherein we use local control loops to break reciprocity at the level of the interactions between the unit cells. We show theoretically and experimentally that first-of-their-kind spatially asymmetric standing waves at all frequencies and unidirectionally amplified propagating waves emerge. These findings realize the mechanical analogue of the non-Hermitian skin effect. They significantly advance the field of active metamaterials for non hermitian physics and open avenues to channel mechanical energy in unprecedented ways.

Long standing waves in a curved canal

1968 ◽  
Vol 34 (4) ◽  
pp. 759-768 ◽  
Author(s):  
B. Johns ◽  
A. M. O. Hamzah
Keyword(s):  
Water Waves ◽  
Wave Amplitude ◽  
Standing Waves ◽  
Low Frequency ◽  
Local Wave ◽  
Low Frequency Waves ◽  
Transverse Oscillations

The dynamics of long water waves are considered in a curved geometry representing a canal bend. The presence of the bend is found to produce a spectrum of transverse oscillations in the canal. The associated dominant amplitudes are evaluated for both tidal periods and higher frequencies representative of tsunamis. It is found that low-frequency waves do not lead to significant transverse amplitudes. For tsunamis, the presence of the bend may result in considerable changes in the local wave amplitude.

scholarly journals Lateral Gradient Ambidextrous Optical Reflection in Self-Organized Left-Handed Chiral Nematic Cellulose Nanocrystals Films

2021 ◽  
Vol 9 ◽  
Author(s):  
Jiawei Tao ◽  
Jiaqi Li ◽  
Xiao Yu ◽  
Lihong Wei ◽  
Yan Xu
Keyword(s):  
Cellulose Nanocrystals ◽  
Self Assembly ◽  
Circularly Polarized ◽  
Optical Reflection ◽  
Self Organized ◽  
Left Handed ◽  
Assembly Method ◽  
Chiral Nematic ◽  
Half Wavelength ◽  
Film Substrate

Artificial photonic materials displaying ordered reflected color patterns are desirable in the field of photonic technologies, however, it is challenging to realize. Here we present that self-assembly of cellulose nanocrystals (CNC) in a tilted cuvette leads to the formation of rainbow color CNC films. We show that the self-organized CNC films enable simultaneous reflection of left-handed circularly polarized (LCP) and right-handed circularly polarized (RCP) light with lateral gradient transmittance ratio (LCP/RCP: 8.7–0.9) and the maximum reflectance value up to ca. 72%. This unique ambidextrous optical reflection arises from left-handed chiral photonic architectures with lateral gradient photonic bandgaps and nematic-like defects at the film-substrate interface and between left-handed photonic bandgap layers acting as a half-wavelength retarder. We demonstrate that the tilted angle self-assembly method provides a feasible step toward color patterning of CNC-based photonic films capable of ambidextrous optical reflection.

Microfabrication for Packaged Biomolecular Unit Cells

2013 ◽  
Author(s):  
Mary-Anne Nguyen ◽  
Andy Sarles
Keyword(s):  
Self Assembly ◽  
Material System ◽  
Stimuli Responsive ◽  
Critical Feature ◽  
Liquid Phases ◽  
Unit Cells ◽  
Droplet Interface Bilayer ◽  
Polymeric Substrates ◽  
Original Amount

This paper focuses on developing a closed fluidic environment for packaging biomolecular unit cells, which consists of a synthetic lipid bilayer and other biomolecules contained in a near solid-state material with two regions that contain hydrophobic oil (i.e. nonpolar solvent) surrounding aqueous droplets. This research provides a stepping-stone towards an autonomic biomolecular material system, whereby a packaged system will allow for precise droplet interface bilayer (DIB) formation without the interference of outside contamination for long-term applications. Also, substrate materials need to maintain droplets and preserve the self-assembly and stimuli-responsive properties of biomolecules within the unit cell. A critical feature of an encapsulating material is that it does not absorb either of the liquid phases required to form DIBs. Oil depletion tests within sealed, polymeric substrates show that polydimethylsiloxane (PDMS) absorbs full volume of injected hexadecane in approximately 27 hours. However, polyurethane substrates maintain the original amount of oil injected even after several weeks. Bilayer lifetime is also monitored within an environment in which the oil is also depleting. The results of this test show the longevity of a DIB to be shorter than oil lifetime. The lipid-encased droplets disconnect after approximately 10 hours, when there is only approximately <60% amount of oil present. In addition, an initial microfluidic substrate is designed such that a single T-junction intersection can be used to form monodisperse droplets within a primary oil-filled channel and a downstream increase in channel width can be used to connect droplets to form DIBs.

Self-assembled plasmonic metamaterials

Nanophotonics ◽  
2013 ◽  
Vol 2 (3) ◽  
pp. 211-240 ◽  
Author(s):  
Stefan Mühlig ◽  
Alastair Cunningham ◽  
José Dintinger ◽  
Toralf Scharf ◽  
Thomas Bürgi ◽  
...  
Keyword(s):  
Self Assembly ◽  
Degrees Of Freedom ◽  
Building Blocks ◽  
Spatial Arrangement ◽  
Plasmonic Nanostructures ◽  
Bottom Up ◽  
Unit Cells ◽  
Amorphous Structures ◽  
Self Assembled ◽  
Novel Applications

AbstractNowadays for the sake of convenience most plasmonic nanostructures are fabricated by top-down nanofabrication technologies. This offers great degrees of freedom to tailor the geometry with unprecedented precision. However, it often causes disadvantages as well. The structures available are usually planar and periodically arranged. Therefore, bulk plasmonic structures are difficult to fabricate and the periodic arrangement causes undesired effects, e.g., strong spatial dispersion is observed in metamaterials. These limitations can be mitigated by relying on bottom-up nanofabrication technologies. There, self-assembly methods and techniques from the field of colloidal nanochemistry are used to build complex functional unit cells in solution from an ensemble of simple building blocks, i.e., in most cases plasmonic nanoparticles. Achievable structures are characterized by a high degree of nominal order only on a short-range scale. The precise spatial arrangement across larger dimensions is not possible in most cases; leading essentially to amorphous structures. Such self-assembled nanostructures require novel analytical means to describe their properties, innovative designs of functional elements that possess a desired near- and far-field response, and entail genuine nanofabrication and characterization techniques. Eventually, novel applications have to be perceived that are adapted to the specifics of the self-assembled nanostructures. This review shall document recent progress in this field of research. Emphasis is put on bottom-up amorphous metamaterials. We document the state-of-the-art but also critically assess the problems that have to be overcome.

Supramolecular structures formed by the self assembly of ionic fullerenes in binary liquid mixtures

2007 ◽  
Vol 22 (11) ◽  
pp. 3029-3035 ◽  
Author(s):  
Tohru Shiga ◽  
Tomoyoshi Motohiro
Keyword(s):  
Self Assembly ◽  
Liquid Mixtures ◽  
Binary Liquid Mixtures ◽  
Supramolecular Structures ◽  
The Self ◽  
Laser Raman Spectroscopy ◽  
Raman Spectroscopic ◽  
Laser Raman ◽  
Binary Liquid ◽  
Unit Cells

The self assembly of C60-N, N′-dimethylpyrrolidinium iodide (C60-DMePyI) in binary liquid mixtures has been investigated. C60-DMePyI self-organized into nanosheets in a mixture of toluene and iodomethane, and aggregated to form nanofibers in toluene. The dimensions of the nanosheets were several micrometers in length and about 100 nm in thickness. Scanning electron microscope observations indicated that a large number of nanorods having a diameter of about 20-nm formed matted nanosheets. When iodomethane alone was used as a solvent, supramolecular structures such as nanofibers and nanosheets were not produced. Structural analyses of the C60-DMePyI aggregates were carried out by laser Raman spectroscopy and x-ray diffraction (XRD). The Raman spectroscopic results suggested that an ordered chain of successive polyiodine units was formed in all the supramolecular aggregates. The XRD studies showed that the crystal systems of the nanosheets and nanofibers were monoclinic, though with different unit cells.

An axisymmetric free surface with a 120 degree angle along a circle

1997 ◽  
Vol 342 ◽  
pp. 403-409 ◽  
Author(s):  
J.-M. VANDEN-BROECK ◽  
JOSEPH B. KELLER
Keyword(s):  
Free Surface ◽  
Wave Amplitude ◽  
Axisymmetric Flow ◽  
Numerical Procedure ◽  
Critical Value ◽  
Circular Ring ◽  
Free Surface Flows ◽  
Local Analysis ◽  
Surface Flows ◽  
Stagnation Points

An axisymmetric flow due to a submerged sink in water of infinite depth is considered, with a stagnation point on the free surface above the sink. Forbes & Hocking (1990) calculated numerically a flow for each value of the Froude number F smaller than a critical value Fc. For F close to Fc there is a ring-shaped bump on the free surface. At F=Fc, the crest of the bump becomes a ring of stagnation points. We use the numerical procedure of Hocking & Forbes to show that the bump is the first crest of a train of axisymmetric waves. The wave amplitude decreases with increasing distance from the source. Then we give a local analysis of axisymmetric free-surface flows with a circular ring of stagnation points. We find flows in which the surface has a discontinuity in slope with an enclosed angle of 120° all along the ring. This behaviour is consistent with the numerical solution for F=Fc near the crest of the bump.

scholarly journals Numerical Analysis of Modified Seabed Topography Due to the Presence of Breakwaters of Varying Reflection Characteristics using Physics-based Morphology Model [SeoulFoam]

2021 ◽  
Vol 33 (4) ◽  
pp. 168-178
Author(s):  
Yong Jun Cho
Keyword(s):  
Boundary Layer ◽  
Numerical Model ◽  
Reflection Coefficient ◽  
Wave Amplitude ◽  
Standing Waves ◽  
Sand Wave ◽  
Sand Waves ◽  
Seabed Topography ◽  
Morphology Model ◽  
Reflection Characteristics

Numerical simulations were implemented to look into the modified seabed topography due to the presence of breakwaters of varying reflection characteristics. The numerical model was composed of OlaFlow, an OpenFoam-based tool box, and a physics-based morphology model [Seoul Foam]. In doing so, the interaction between the seabed, which undergoes deformation due to siltation and scouring, and the incoming waves was described using Dynamic Mesh. The rubble-mound, vertical, and curved slit caisson breakwaters with varying reflection characteristics resulted in standing waves that differ from each other, shown to have a significant influence on the seabed topography. These results are in line with Nielsen’s study (1993) that sands saltated under the surface nodes of standing waves, where the near-bed velocities are most substantial, convected toward the surface antinodes by boundary-layer drift. Moreover, the crest of sand waves was formed under the surface antinodes of standing waves, and the trough of sand waves was formed under the surface antinodes. In addition, sand wave amplitude reaches its peak in the curved slit caisson with a significant reflection coefficient, and the saltation of many grains of sand would cause this phenomenon due to the increased near-bed velocity under the nodes when the reflection coefficient is getting large.

Generation of sub-half-wavelength micro-optical traps by dichroic evanescent standing waves

2007 ◽  
Vol 16 (5) ◽  
pp. 1295-1299
Author(s):  
Zhang Jing ◽  
Zhang Tian-Cai ◽  
Wang Jun-Min ◽  
Peng Kun-Chi
Keyword(s):  
Standing Waves ◽  
Optical Traps ◽  
Half Wavelength
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