Article
Physics, Fluids & Plasmas
Vladimir Parfenyev
Summary: This study conducts a numerical hyperviscous study of the spatial vorticity profile within a coherent vortex dipole, which emerges from an inverse turbulent cascade in a finite two-dimensional periodic domain. The results show that the vorticity profile becomes steeper with a spatially homogeneous forcing and finite pumping scale, with the difference increasing with the pumping scale but decreasing with the Reynolds number at the forcing scale.
Article
Physics, Multidisciplinary
M. T. Wheeler, H. Salman, M. O. Borgh
Summary: The study reveals that the relaxation dynamics of quantum turbulence in a two-component Bose-Einstein condensate with half-quantum vortices shows temporal scaling at different time scales for the number of vortices and correlation lengths. At early times, this scaling is strongly dependent on the relative strength of the inter-species interaction, while at later times it becomes universal and independent of the inter-species interaction, approaching the behavior observed in a scalar Bose-Einstein condensate.
Article
Mechanics
Dmitriy Zhigunov, Roman O. Grigoriev
Summary: This paper presents new classes of unstable recurrent solutions of the two-dimensional Euler equation with periodic boundary conditions. These solutions resemble the recurrent solutions of the Navier-Stokes equation, known as exact coherent structures. The Euler equation solutions come in infinite-dimensional continuous families, are connected to different types of solutions, and exhibit weak instability, leading to the frequent occurrence of these solutions in fully developed turbulence.
JOURNAL OF FLUID MECHANICS
(2023)
Article
Physics, Multidisciplinary
Xiang-Pei Liu, Xing-Can Yao, Youjin Deng, Xiao-Qiong Wang, Yu-Xuan Wang, Chun-Jiong Huang, Xiaopeng Li, Yu-Ao Chen, Jian-Wei Pan
Summary: Researchers generated a large number of vortices in a fermionic superfluid and observed their annihilation dynamics and spatial distribution. The vortices were found to follow algebraic scaling laws with exponents consistent with two-dimensional universality. Simulations of the classical XY model showed good agreement between numerical and experimental behaviors.
PHYSICAL REVIEW LETTERS
(2021)
Article
Multidisciplinary Sciences
Lia Siegelman, William R. Young
Summary: The evolution of unforced and weakly damped two-dimensional turbulence over random rough topography can exhibit two extreme states. When the initial kinetic energy is high, the evolution is determined by the spontaneous formation and interaction of coherent axisymmetric vortices, which mix the background potential vorticity to homogeneity. When the initial kinetic energy is low, the vortices still form but become locked to topographic features, resulting in spatial variation of the background potential vorticity.
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
(2023)
Article
Physics, Multidisciplinary
Guoquan Yang, Siyu Xie, Yan Zhao, Jingjing Jin, Suying Zhang
Summary: We studied the dynamics of ring dark solitons in a two-dimensional dipolar Bose-Einstein condensate and found that the effect of dipolar interaction on the soliton dynamics is different from that in a non-dipolar condensate. The dipolar interaction can induce collapse of shallow ring dark solitons and the formation of vortex-antivortex pairs. When the dipolar atoms are oriented non-vertically to the condensate, the solitons shrink to an elliptical configuration and decay into lump solitons or vortex-antivortex pairs, with phenomena such as vortex recombination, annihilation, oblique collisions, and catching up.
PHYSICA A-STATISTICAL MECHANICS AND ITS APPLICATIONS
(2023)
Article
Physics, Multidisciplinary
Romain Dubessy, Juan Polo, Helene Perrin, Anna Minguzzi, Maxim Olshanii
Summary: The protocol presented in the study allows for the creation of moving, robust dispersive shock waves in interacting one-dimensional Bose fluids, which are demonstrated to be oscillatory and resistant to thermal fluctuations. These shock waves are shown to be universal and controllable across a spectrum of interaction strengths, and the proposed dynamics extend the dispersive-shock-wave paradigm to the many-body regime, making them accessible for ultracold atom experiments.
PHYSICAL REVIEW RESEARCH
(2021)
Article
Mechanics
Suresh Behara, Venu Chandra, N. R. Prashanth
Summary: This study numerically investigates the three-dimensional transition in the wake of two tandem co-rotating cylinders. The results show that the rotation of the cylinders and the change of the streamwise gaps both affect the transition modes and the characteristics of the near-wake flow.
JOURNAL OF FLUID MECHANICS
(2022)
Article
Physics, Fluids & Plasmas
B. H. Burgess
Summary: This study investigates the statistics of clustered and free long-lived vortices in forced-dissipative two-dimensional turbulence. It finds that perfectly polarized clusters exhibit a scale-invariant distribution of areas, while the number density of free vortices scales differently. The number of vortices in perfect clusters decreases over time, while the number of free vortices increases as smaller vortices are ejected from clusters. Large clusters are disassembled more quickly than smaller clusters, and they exhibit different scaling laws. A semiempirical mean-field theory is developed for the vortices in perfectly polarized clusters.
PHYSICAL REVIEW FLUIDS
(2022)
Article
Physics, Multidisciplinary
A. N. Doludenko, S. V. Fortova, I. V. Kolokolov, V. V. Lebedev
Summary: This study examines the state of a two-dimensional fluid in a finite box resulting from an inverse cascade supported by a permanent pumping through analytical and numerical approaches. Two different states are identified: one dominated by coherent vortices with a well-defined profile, and the other dominated by chaotic large-scale fluctuations. The realized state depends on the ratio vk2f/alpha, where v is the viscosity coefficient, kf is the wave vector of the pumping force, and alpha is the bottom friction coefficient.
Article
Physics, Multidisciplinary
J. Chai, L. Fang
Summary: In this study, the late dynamics of large-scale vortices in freely decaying two-dimensional flows with periodic boundary conditions have been investigated through direct numerical simulations. It was found that the theories of point vortices can be approximately applied to various periodic conditions, but the dynamics in real flows can switch among different motions. This study also observed a unique wandering motion phenomenon in which the weakest vortex can migrate among different periods while the other two vortices co-rotate, similar to the physics of current flow. Additionally, the merging process of large-scale vortices can be described using the skewness of vorticity.
Article
Mechanics
Xander M. de Wit, Adrian van Kan, Alexandros Alexakis
Summary: In this study, direct numerical simulations of thin-layer flow were used to investigate whether the bistable range survives as the domain size and turbulence intensity are increased. The research found that the bistable range grows as the box size and/or Reynolds number Re are increased.
JOURNAL OF FLUID MECHANICS
(2022)
Article
Mechanics
Brodie C. Pearson, Jenna L. Pearson, Baylor Fox-Kemper
Summary: The study proposes new relations to diagnose energy and enstrophy dissipation rates in anisotropic two-dimensional turbulence, using second-order advective structure functions. These new relations show improvement over existing methods through increased accuracy, insensitivity to sampling direction, and lower temporal and spatial variability. Advective structure functions have benefits under weakly anisotropic conditions, becoming increasingly important as third-order structure functions become inappropriate.
JOURNAL OF FLUID MECHANICS
(2021)
Article
Physics, Applied
Jiamei Kong, Rukuan Wu
Summary: We investigated the dynamics of vortices in a homogeneous two-dimensional Bose-Einstein condensate by considering the variation in condensate density. Our results demonstrate that the condensate density variation plays a crucial role when two vortices are in close proximity. Through the use of the time-dependent Lagrangian functional method and numerical simulations, we explored the variation of interaction strength between vortices with the same or different topological charges as a function of distance, and extended these findings to the case of multiple vortices. The numerical simulations confirmed the validity of our theoretical approach.
MODERN PHYSICS LETTERS B
(2022)
Article
Physics, Multidisciplinary
Adam Griffin, Giorgio Krstulovic, Victor S. L'vov, Sergey Nazarenko
Summary: We present an exact unique constant-flux power-law analytical solution for the wave kinetic equation, applicable for ak << 1. Our theory describes acoustic turbulence in 2D Bose-Einstein condensates, and the corresponding spectrum is confirmed through numerical simulations.
PHYSICAL REVIEW LETTERS
(2022)
Article
Mechanics
G. Boffetta, F. Toselli, M. Manfrin, S. Musacchio
Summary: This study conducted laboratory experiments and numerical simulations to investigate the effects of vertical confinement on freely decaying rotating turbulent flows. The results show that vertical confinement significantly impacts the formation of large-scale columnar vortices and delays the development of cyclone-anticyclone asymmetry. The comparison between experimental and numerical results demonstrates the robustness of the findings.
JOURNAL OF TURBULENCE
(2021)
Article
Mechanics
Marta Magnani, Stefano Musacchio, Guido Boffetta
Summary: The study revealed that in the absence of particle inertia, the particle-laden phase behaves as a denser fluid, while particles with large inertia affect the evolution of turbulent flow and lead to particle clustering.
JOURNAL OF FLUID MECHANICS
(2021)
Article
Multidisciplinary Sciences
M. Shavit, N. Vladimirova, G. Falkovich
Summary: This note discusses the broken and emerging scale invariance of turbulence, focusing on the non-local interactions that may lead to scale-invariant statistics of mode amplitudes known as Kolmogorov multipliers. The hypothesis put forward suggests that extreme non-locality of interactions plays a crucial role in the invariance of multipliers. This study provides a unique opportunity for an analytical investigation of emerging scale invariance in systems with strong interactions.
PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY A-MATHEMATICAL PHYSICAL AND ENGINEERING SCIENCES
(2022)
Article
Multidisciplinary Sciences
Guido Boffetta, Stefano Musacchio
Summary: In this article, the effects of dimensional confinement on the evolution of incompressible Rayleigh-Taylor mixing are studied through numerical simulations. It is found that confinement to two-dimensional flow accelerates the mixing process, increases the speed of the mixing layer, and affects the correlations between the density and velocity fields, as well as the efficiency of mass transfer.
PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY A-MATHEMATICAL PHYSICAL AND ENGINEERING SCIENCES
(2022)
Article
Physics, Multidisciplinary
Karl Lydon, Sergey Nazarenko, Jason Laurie
Summary: Understanding vortex interactions is crucial for understanding turbulence. In this study, the dynamics of point vortex dipoles interacting with vortex structures were investigated using an idealized point vortex model. The results shed light on dipole size evolution, stability properties of vortex clusters, and the role of dipole-cluster interactions in turbulent mixing in 2D quantum turbulence.
JOURNAL OF PHYSICS A-MATHEMATICAL AND THEORETICAL
(2022)
Article
Physics, Fluids & Plasmas
L. Puggioni, G. Boffetta, S. Musacchio
Summary: Through numerical simulations, the dynamics of a dilute solution of rigid rodlike polymers in a viscous fluid at low Reynolds numbers was studied. It was found that the rotational dynamics of polymers can lead to chaotic flow and increased mixing efficiency. The effects observed are dimensionally independent, but stronger in two dimensions due to different rotational degrees of freedom of the rods.
PHYSICAL REVIEW FLUIDS
(2022)
Article
Physics, Fluids & Plasmas
M. Borgnino, G. Boffetta, M. Cencini, F. De Lillo, K. Gustavsson
Summary: In this article, the swimming behavior of aquatic microorganisms and their interaction with flows are studied. The results show that the alignment of the swimming direction with the local velocity is a general phenomenon in Kolmogorov flows. Additionally, the presence of unsteady fluctuations affects the accumulation behavior of microorganisms.
PHYSICAL REVIEW FLUIDS
(2022)
Article
Clinical Neurology
Utkarsh Tripathi, Liron Mizrahi, Martin Alda, Gregory Falkovich, Shani Stern
Summary: This study aimed to improve the prediction of response to lithium and develop a diagnostic algorithm for bipolar disorder using information theory-derived features. The addition of these features significantly improved classification accuracy, distinguishing patients from controls and lithium responders from non-responders.
Article
Chemistry, Physical
Nuno A. M. Araujo, Liesbeth M. C. Janssen, Thomas Barois, Guido Boffetta, Itai Cohen, Alessandro Corbetta, Olivier Dauchot, Marjolein Dijkstra, William M. Durham, Audrey Dussutour, Simon Garnier, Hanneke Gelderblom, Ramin Golestanian, Lucio Isa, Gijsje H. Koenderink, Hartmut Loewen, Ralf Metzler, Marco Polin, C. Patrick Royall, Andela Saric, Anupam Sengupta, Cecile Sykes, Vito Trianni, Idan Tuval, Nicolas Vogel, Julia M. Yeomans, Iker Zuriguel, Alvaro Marin, Giorgio Volpe
Summary: Self-organisation is the spontaneous emergence of spatio-temporal structures and patterns from the interaction of smaller individual units. Confinement can mediate and control self-organisation by limiting the translational and rotational degrees of freedom, acting as a catalyst or inhibitor. By constraining the self-organisation process in soft-matter systems, confinement can actively steer the emergence or suppression of collective phenomena in space and time.
Article
Physics, Fluids & Plasmas
Jason Laurie, Andrew W. Baggaley
Summary: We conducted a numerical study on finite-temperature superfluid turbulence using the vortex filament model for superfluid helium. The phenomenon of vorticity locking between the normal and superfluid components was examined across a range of temperatures using two different structures of external normal fluid drive. Our analysis showed that vorticity locking increases with temperature, resulting in stronger superfluid polarization and deviations from Gaussian statistics with a higher likelihood of extreme fluctuations. We also investigated how these properties affect the pressure field and attempted to verify a theoretical quantum signature within the spatial pressure spectrum, specifically the Pk proportional to k-7/3 relationship.
PHYSICAL REVIEW FLUIDS
(2023)
Article
Multidisciplinary Sciences
Jonathan Skipp, Jason Laurie, Sergey V. Nazarenko
Summary: This study derives a model for the dynamics of light in a spatially nonlocal, nonlinear optical medium, and uses it to study the stationary spectra of Schrodinger-Helmholtz wave turbulence. The model allows for a rigorous and self-consistent derivation of the semilocal approximation model of the wave kinetic equations, revealing the characteristics of energy downscale transfer and waveaction upscale transfer in a forced-dissipated setup.
PROCEEDINGS OF THE ROYAL SOCIETY A-MATHEMATICAL PHYSICAL AND ENGINEERING SCIENCES
(2023)
Article
Physics, Fluids & Plasmas
Jonathan Skipp, Jason Laurie, Sergey Nazarenko
Summary: We rigorously derive a precise point vortex model from the two-dimensional nonlinear Schrodinger equation, considering the Hamiltonian perspective. This derivation is carried out in the limit of well-separated, subsonic vortices on a spatially infinite strong condensate. As a result, we accurately calculate the self-energy of an isolated elementary Pitaevskii vortex.
Article
Physics, Fluids & Plasmas
L. Puggioni, G. Boffetta, S. Musacchio
Summary: This study presents numerical evidence of a new state of bacterial turbulence in confined domains. The researchers discovered the formation of a stable, ordered state in which the angular momentum symmetry is broken, achieved by self-organization of a turbulent-like flow into a single, giant vortex. The study also provides estimates for the temporal and spatial scales of a suitable experimental setup comparable with the numerical findings.
Article
Physics, Fluids & Plasmas
G. Boffetta, S. Musacchio
Summary: In this study, a numerical investigation was conducted to examine the turbulent evolution of the mixing layer formed by the Rayleigh-Taylor instability in circular and spherical geometries. The results revealed that the convergent geometry caused the center of the mixing layer to drift towards the center of the domain, and a simple geometric relation based on mass conservation was derived to explain this inward drift. Furthermore, an inward-outward asymmetry in the radial profiles was observed in the late stage of the evolution.
Article
Physics, Fluids & Plasmas
N. Vladimirova, M. Shavit, S. Belan, G. Falkovich
Summary: When two resonantly interacting modes are in contact with a thermostat, their statistics is exactly Gaussian and the modes are statistically independent despite strong interaction. However, in cascades of noise-driven systems, the statistics is never close to Gaussian, whether interaction is strong or noise is weak. Surprisingly, the mutual information between modes increases and entropy decreases when interaction strength decreases.
