Experimental observations of non-Gaussian behavior and stringlike cooperative dynamics in concentrated quasi-two-dimensional colloidal liquids

We investigate the performance of standard stochastic models of single-particle dispersion in two-dimensional turbulence. Owing to the presence of coherent vortices, particle dispersion in two-dimensional turbulence is characterized by a non-Gaussian velocity distribution and a non-exponential velocity autocorrelation, and it cannot be properly captured by either linear or nonlinear stochastic models with a single component process. Based on physical and dynamical considerations, we introduce a family of two-process stochastic models that provide a better parameterization of turbulent dispersion in rotating barotropic flows.

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Closure theories with non‐Gaussian restarts for truncated two‐dimensional turbulence

Physics of Fluids ◽

10.1063/1.868139 ◽

1994 ◽

Vol 6 (9) ◽

pp. 3153-3163 ◽

Cited By ~ 21

Author(s):

J. S. Frederiksen ◽

A. G. Davies ◽

R. C. Bell

Keyword(s):

Two Dimensional ◽

Non Gaussian

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Cooperative dynamics in a class of coupled two-dimensional oscillators

Physical Review E ◽

10.1103/physreve.67.016210 ◽

2003 ◽

Vol 67 (1) ◽

Cited By ~ 13

Author(s):

J. A. Acebrón ◽

W.-J. Rappel ◽

A. R. Bulsara

Keyword(s):

Two Dimensional ◽

Cooperative Dynamics

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Non-Gaussian Random Wave Simulation by Two-Dimensional Fourier Transform and Linear Oscillator Response to Morison Force

Journal of Offshore Mechanics and Arctic Engineering ◽

10.1115/1.2783888 ◽

2007 ◽

Vol 129 (4) ◽

pp. 327-334 ◽

Cited By ~ 6

Author(s):

Xiang Yuan Zheng ◽

Torgeir Moan ◽

Ser Tong Quek

Keyword(s):

Fourier Transform ◽

Time Domain ◽

Two Dimensions ◽

Second Order ◽

Linear Oscillator ◽

Interaction Matrix ◽

Random Wave ◽

Two Dimensional ◽

Near Surface ◽

Non Gaussian

The one-dimensional fast Fourier transform (FFT) has been applied extensively to simulate Gaussian random wave elevations and water particle kinematics. The actual sea elevations/kinematics exhibit non-Gaussian characteristics that can be represented mathematically by a second-order random wave theory. The elevations/kinematics formulations contain frequency sum and difference terms that usually lead to expensive time-domain dynamic analyses of offshore structural responses. This study aims at a direct and efficient two-dimensional FFT algorithm for simulating the frequency sum terms. For the frequency-difference terms, inverse FFT and forward FFT are implemented, respectively, across the two dimensions of the wave interaction matrix. Given specified wave conditions, the statistics of simulated elevations/kinematics compare well with not only the empirical fits but also the analytical solutions based on a modified eigenvalue/eigenvector approach, while the computational effort of simulation is very economical. In addition, the stochastic analyses in both time domain and frequency domain show that, attributable to the second-order nonlinear wave effects, the near-surface Morison force and induced linear oscillator response are more non-Gaussian than those subjected to Gaussian random waves.

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Non-Gaussian, transiently anomalous and ergodic self-diffusion of flexible dumbbells in crowded two-dimensional environments: coupled translational and rotational motions

10.1101/2021.09.06.459157 ◽

2021 ◽

Author(s):

Kolja Klett ◽

Andrey G Cherstvy ◽

Jaeoh Shin ◽

Igor M Sokolov ◽

Ralf Metzler

Keyword(s):

Relative Motion ◽

Center Of Mass ◽

Scaling Exponent ◽

Two Dimensional ◽

Particle Structure ◽

Self Diffusion ◽

Experimental Systems ◽

Long Time ◽

Non Gaussian ◽

Dynamics Simulations

We employ Langevin-dynamics simulations to unveil non-Brownian and non-Gaussian center-of-mass self-diffusion of massive flexible dumbbell-shaped particles in crowded two-dimensional solutions. We also study the intra-dumbbell dynamics due to the relative motion of the two constituent elastically-coupled disks. Our main focus is on effects of the crowding fraction φ and the particle structure on the diffusion characteristics. We evaluate the time-averaged mean-squared displacement (TAMSD), the displacement probability-density function (PDF) and the displacement autocorrelation function (ACF) of the dimers. For the TAMSD at highly crowded conditions of dumbbells, e.g., we observe a transition from the short-time ballistic behavior, via an intermediate subdiffusive regime, to long-time Brownian-like spreading dynamics. The crowded system of dimers exhibits two distinct diffusion regimes distinguished by the scaling exponent of the TAMSD, the dependence of the diffusivity on φ, and the features of the displacement-ACF. We attribute these regimes to a crowding-induced transition from a viscous to a viscoelastic diffusion medium upon growing φ. We also analyze the relative motion in the dimers, finding that larger φ suppress their vibrations and yield strongly non-Gaussian PDFs of rotational displacements. For the diffusion coefficients D(φ) of translational and rotational motion of the dumbbells an exponential decay with φ for weak and a power-law D(φ) ∝ (φ - φ*)2.4 for strong crowding is found. A comparison of simulation results with theoretical predictions for D(φ) is discussed and some relevant experimental systems are overviewed.

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Highly Accurate Multi-Invariance ESPRIT for DOA Estimation with a Sparse Array

Mathematical Problems in Engineering ◽

10.1155/2019/5325817 ◽

2019 ◽

Vol 2019 ◽

pp. 1-7

Author(s):

Chen Gu ◽

Hong Hong ◽

Yusheng Li ◽

Xiaohua Zhu ◽

Jin He

Keyword(s):

Doa Estimation ◽

Invariance Property ◽

Two Dimensional ◽

Sparse Array ◽

Half Wavelength ◽

Vector Sensors ◽

Matrix Blocks ◽

Simulation Results ◽

Non Gaussian ◽

Array Geometry

This paper proposes a multi-invariance ESPRIT-based method for estimation of 2D direction (MIMED) of multiple non-Gaussian monochromatic signals using cumulants. In the MIMED, we consider an array geometry containing sparse L-shaped diversely polarized vector sensors plus an arbitrarily-placed single polarized scalar sensor. Firstly, we define a set of cumulant matrices to construct two matrix blocks with multi-invariance property. Then, we develop a multi-invariance ESPRIT-based algorithm with aperture extension using the defined matrix blocks to estimate two-dimensional directions of the signals. The MIMED can provide highly accurate and unambiguous direction estimates by extending the array element spacing beyond a half-wavelength. Finally, we present several simulation results to demonstrate the superiority of the MIMED.

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