scholarly journals Density Fluctuations and Energy Spectra of 3D Bacterial Suspensions

Soft Matter ◽  
2021 ◽  
Author(s):  
Zhengyang Liu ◽  
Wei Zeng ◽  
Xiaolei Ma ◽  
Xiang Cheng
Keyword(s):  
Density Fluctuations ◽  
Energy Spectra ◽  
Nonequilibrium Dynamics ◽  
Two Dimensional ◽  
Anomalous Density

Giant number fluctuations are often considered as a hallmark of the emergent nonequilibrium dynamics of active fluids. However, these anomalous density fluctuations have only been reported experimentally in two-dimensional dry...

scholarly journals Unfolding energy spectra of double-periodicity two-dimensional systems: Twisted bilayer graphene and MoS2 on graphene

2018 ◽  
Vol 2 (1) ◽  
Author(s):  
Yu-ichiro Matsushita ◽  
Hirofumi Nishi ◽  
Jun-ichi Iwata ◽  
Taichi Kosugi ◽  
Atsushi Oshiyama
Keyword(s):  
Bilayer Graphene ◽  
Energy Spectra ◽  
Two Dimensional ◽  
Twisted Bilayer Graphene

Structural characteristics of a developing turbulent planar jet

1986 ◽  
Vol 163 ◽  
pp. 227-256 ◽  
Author(s):  
F. O. Thomas ◽  
V. W. Goldschmidt
Keyword(s):  
Large Scale ◽  
Structural Characteristics ◽  
Energy Spectra ◽  
Two Dimensional ◽  
Structural Pattern ◽  
Potential Core ◽  
Planar Jet ◽  
Fluctuation Phase ◽  
Oriented Parallel ◽  
Phase Angles

An experimental study of the developing structural characteristics of a two-dimensional jet in an extremely quiet environment was performed. The jet, at an exit Reynolds number of 6000 and with fluctuation intensity under 0.2% at the mouth, was operated within a large anechoic room. Measurements of energy spectra, fluctuation phase angles and two-dimensionality led to the inference of structural patterns in the flow. These patterns are initially characterized by relatively strong symmetric modes exhibiting limited two-dimensionality and oriented parallel to the mouth of the jet. Subsequent downstream evolution led to the formation of an antisymmetric pattern beyond the jet potential core and the associated development of extended structures possessing a definite large lateral inclination. The results of this work suggest a developing large-scale structural pattern more complicated than previously supposed.

scholarly journals Stone–Wales defects preserve hyperuniformity in amorphous two-dimensional networks

2021 ◽  
Vol 118 (3) ◽  
pp. e2016862118
Author(s):  
Duyu Chen ◽  
Yu Zheng ◽  
Lei Liu ◽  
Ge Zhang ◽  
Mohan Chen ◽  
...  
Keyword(s):  
2D Materials ◽  
Single Layer ◽  
Salient Feature ◽  
Density Fluctuations ◽  
Wave Number ◽  
Static Structure Factor ◽  
Two Dimensional ◽  
Static Structure ◽  
Topological Transformation ◽  
Amorphous Graphene

Disordered hyperuniformity (DHU) is a recently discovered novel state of many-body systems that possesses vanishing normalized infinite-wavelength density fluctuations similar to a perfect crystal and an amorphous structure like a liquid or glass. Here, we discover a hyperuniformity-preserving topological transformation in two-dimensional (2D) network structures that involves continuous introduction of Stone–Wales (SW) defects. Specifically, the static structure factor S(k) of the resulting defected networks possesses the scaling S(k)∼kα for small wave number k, where 1≤α(p)≤2 monotonically decreases as the SW defect concentration p increases, reaches α≈1 at p≈0.12, and remains almost flat beyond this p. Our findings have important implications for amorphous 2D materials since the SW defects are well known to capture the salient feature of disorder in these materials. Verified by recently synthesized single-layer amorphous graphene, our network models reveal unique electronic transport mechanisms and mechanical behaviors associated with distinct classes of disorder in 2D materials.

Two‐dimensional nonequilibrium dynamics of domain‐wall motion

1991 ◽  
Vol 69 (8) ◽  
pp. 5757-5759 ◽  
Author(s):  
G. N. Patterson ◽  
R. C. Giles ◽  
F. B. Humphrey
Keyword(s):  
Domain Wall ◽  
Wall Motion ◽  
Domain Wall Motion ◽  
Nonequilibrium Dynamics ◽  
Two Dimensional

Energy spectra of steady two-dimensional turbulent flows

2000 ◽  
Vol 61 (6) ◽  
pp. 6572-6577 ◽  
Author(s):  
Norbert Schorghofer
Keyword(s):  
Turbulent Flows ◽  
Energy Spectra ◽  
Two Dimensional

scholarly journals Particle Acceleration in Collisionless Magnetic Reconnection

2001 ◽  
Vol 203 ◽  
pp. 555-557
Author(s):  
P. K. Browning ◽  
G. E. Vekstein
Keyword(s):  
Magnetic Field ◽  
Field Component ◽  
Charged Particles ◽  
Energy Spectra ◽  
Uniform Field ◽  
Two Dimensional ◽  
Point Field ◽  
Field Geometry ◽  
Collisionless Reconnection ◽  
Accelerated Particles

We investigate the acceleration of charged particles in the framework of collisionless reconnection. A steady reconnection scenario is considered, with a two dimensional X-point magnetic field geometry having also a uniform field component transverse to the plane of the X-point field, and an inductive electric field generating an inflow of particles. Test particle trajectories are studied, and the energy spectra of the accelerated particles are determined.

scholarly journals On inertial-range scaling laws

1996 ◽  
Vol 306 ◽  
pp. 167-181 ◽  
Author(s):  
John C. Bowman
Keyword(s):  
Steady State ◽  
High Resolution ◽  
Scaling Laws ◽  
State Energy ◽  
Three Dimensional ◽  
Inertial Range ◽  
Energy Spectra ◽  
Two Dimensional ◽  
Unified Framework ◽  
Asymptotic Nature

Inertial-range scaling laws for two- and three-dimensional turbulence are re-examined within a unified framework. A new correction to Kolmogorov's k−5/3 scaling is derived for the energy inertial range. A related modification is found to Kraichnan's logarithmically corrected two-dimensional enstrophy-range law that removes its unexpected divergence at the injection wavenumber. The significance of these corrections is illustrated with steady-state energy spectra from recent high-resolution closure computations. Implications for conventional numerical simulations are discussed. These results underscore the asymptotic nature of inertial-range scaling laws.

Infrared Reynolds number dependency of the two-dimensional inverse energy cascade

2011 ◽  
Vol 667 ◽  
pp. 463-473 ◽  
Author(s):  
ANDREAS VALLGREN
Keyword(s):  
Reynolds Number ◽  
Cascade Range ◽  
Energy Cascade ◽  
Energy Spectra ◽  
Small Scale ◽  
Two Dimensional ◽  
Inverse Energy Cascade ◽  
Linear Friction ◽  
Non Local ◽  
Reynolds Number Dependency

High-resolution simulations of forced two-dimensional turbulence reveal that the inverse cascade range is sensitive to an infrared Reynolds number, Reα = kf/kα, where kf is the forcing wavenumber and kα is a frictional wavenumber based on linear friction. In the limit of high Reα, the classic k−5/3 scaling is lost and we obtain steeper energy spectra. The sensitivity is traced to the formation of vortices in the inverse energy cascade range. Thus, it is hypothesized that the dual limit Reα → ∞ and Reν = kd/kf → ∞, where kd is the small-scale dissipation wavenumber, will lead to a steeper energy spectrum than k−5/3 in the inverse energy cascade range. It is also found that the inverse energy cascade is maintained by non-local triad interactions.

scholarly journals Enhanced hyperuniformity from random reorganization

2017 ◽  
Vol 114 (17) ◽  
pp. 4294-4299 ◽  
Author(s):  
Daniel Hexner ◽  
Paul M. Chaikin ◽  
Dov Levine
Keyword(s):  
Particle Density ◽  
Thermal Fluctuations ◽  
Close Packing ◽  
Density Fluctuations ◽  
Nonequilibrium Dynamics ◽  
Limiting Behavior ◽  
Equilibrium Dynamics ◽  
Absorbing State ◽  
Maximum Value ◽  
Temperature Equilibrium

Diffusion relaxes density fluctuations toward a uniform random state whose variance in regions of volume v=ℓd scales as σρ2≡⟨ρ2(ℓ)⟩−⟨ρ⟩2∼ℓ−d. Systems whose fluctuations decay faster, σρ2∼ℓ−λ with d<λ≤d+1, are called hyperuniform. The larger λ, the more uniform, with systems like crystals achieving the maximum value: λ=d+1. Although finite temperature equilibrium dynamics will not yield hyperuniform states, driven, nonequilibrium dynamics may. Such is the case, for example, in a simple model where overlapping particles are each given a small random displacement. Above a critical particle density ρc, the system evolves forever, never finding a configuration where no particles overlap. Below ρc, however, it eventually finds such a state, and stops evolving. This “absorbing state” is hyperuniform up to a length scale ξ, which diverges at ρc. An important question is whether hyperuniformity survives noise and thermal fluctuations. We find that hyperuniformity of the absorbing state is not only robust against noise, diffusion, or activity, but that such perturbations reduce fluctuations toward their limiting behavior, λ→d+1, a uniformity similar to random close packing and early universe fluctuations, but with arbitrary controllable density.

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