Article
Physics, Fluids & Plasmas
Yuanting Chen, Benno Rumpf
Summary: The study reveals that there are two opposing dynamics when solitary waves interact with random Rayleigh-Jeans distributed waves, depending on the dynamical property of the solitary wave and the statistical property of the thermal waves. The transition between the two dynamics results in an increase in wave entropy.
Article
Mechanics
Andre N. Souza, Tyler Lutz, Glenn R. Flierl
Summary: We analyze a class of stochastic advection problems by conditionally averaging the passive tracer equation with respect to a given flow state. We obtain expressions for the turbulent diffusivity as a function of the flow statistics spectrum. The ensemble average turbulent flux is expressed as a linear operator that acts on the ensemble average of the tracer.
JOURNAL OF FLUID MECHANICS
(2023)
Article
Physics, Fluids & Plasmas
Abdelkader El Makouri, Abdallah Slaoui, Rachid Ahl Laamara
Summary: In this paper, measurement-based quantum thermal machines are studied and the necessary condition for positive work and bounds on the ratio of fluctuations for a spin-1/2 quantum Otto heat engine are derived. The role of initial coherence on efficiency and relative fluctuations is also analyzed.
Article
Mechanics
Te-Yao Chiu, Chien-Chou Tseng, Chien-Cheng Chang, Yi-Ju Chou
Summary: This study investigated the influence of coherent structures on the aerodynamic forces acting on an aerofoil. The results showed that these structures have a significant impact on drag and lift forces, and can be identified and quantified using the SPOD algorithm and vorticity force analysis.
JOURNAL OF FLUID MECHANICS
(2023)
Article
Mechanics
Xiaoning Wang, Jianchun Wang, Shiyi Chen
Summary: This study investigates the effects of compressibility on the statistics and coherent structures of a temporally developing mixing layer through numerical simulations. The results show that as the convective Mach number increases, the streamwise dissipation becomes more effective in suppressing turbulent kinetic energy. At low convective Mach numbers, the mixing layer is accompanied by spanwise Kelvin-Helmholtz rollers, while at higher convective Mach numbers, large-scale high- and low-speed structures dominate. The study also reveals a correlation between high-shearing motions on top of low-speed structures and the clustering of small-scale vortical structures.
JOURNAL OF FLUID MECHANICS
(2022)
Article
Mechanics
Ethan Pickering, Georgios Rigas, Oliver T. Schmidt, Denis Sipp, Tim Colonius
Summary: Linear resolvent analysis of turbulent mean-flow fields can qualitatively capture characteristics of coherent structures in turbulent flows. By using a data-driven approach to optimize the eddy viscosity, the agreement between resolvent and SPOD modes can be substantially improved, reaching over 90% agreement at certain frequencies. A fixed model for eddy viscosity with a single constant can also provide substantial agreement between different modes in turbulent jets.
JOURNAL OF FLUID MECHANICS
(2021)
Article
Environmental Sciences
Masoud Kazem, Hossein Afzalimehr, Jueyi Sui
Summary: The study found that vegetation patches in a channel can affect the formation of vortex structures, including both vertical and horizontal vortexes. The flow passing through the patch and side flow around the patch have a considerable effect on the flow structures beyond the patch, especially for channels with small patches in the bed.
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
Mechanics
Wu-ting Tsai, Guan-hung Lu
Summary: In this study, numerical simulations were conducted to reveal the vortical structures of Langmuir circulations (LCs) and quasi-streamwise vortices (QSVs), and their interactions. LCs manifest themselves by inducing wind-aligned streaks on the surface, while QSVs accumulate beneath the windward surface and dominate the distribution. The formation of QSVs enhances the production of streamwise enstrophy and differs from the coherent vortical structures (CVSs) in wall turbulence.
JOURNAL OF FLUID MECHANICS
(2023)
Article
Mechanics
Hirotaka Maeyama, Soshi Kawai
Summary: Near-wall turbulence structures and generation in the wall-modelled large-eddy simulation (WMLES) are investigated by comparing with direct numerical simulation (DNS). The near-wall statistical structures producing turbulence are found to exist even in the WMLES, although they are numerically elongated. The near-wall turbulence structures in the WMLES are suggested to be coherent structures with alternating low- and high-speed fluids in the spanwise direction.
JOURNAL OF FLUID MECHANICS
(2023)
Article
Mechanics
Michael C. Krygier, Joshua L. Pughe-Sanford, Roman O. Grigoriev
Summary: A theoretical framework based on exact coherent structures (ECSs) is studied for modelling fluid turbulence, but direct evidence for the role of ECSs in experimental turbulent flows is still lacking, and further experimental tests are needed to validate this framework.
JOURNAL OF FLUID MECHANICS
(2021)
Article
Physics, Multidisciplinary
Josselin Garnier, Kilian Baudin, Adrien Fusaro, Antonio Picozzi
Summary: By increasing the nonlinearity, a system self-organizes into an incoherent localized structure containing hidden coherent soliton states, which are fully immersed in random wave fluctuations and can hardly be identified in usual spatial or spectral domains but clearly unveiled in phase-space representation. The hidden solitons are stabilized and trapped by the incoherent localized structure, and can be observed in nonlocal nonlinear optics experiments through the measurement of the spatial spectrogram. This regime sheds new light on the quantum-to-classical correspondence with gravitational interactions.
PHYSICAL REVIEW LETTERS
(2021)
Article
Agronomy
I. M. Cely-Toro, L. Mortarini, C. Q. Dias Junior, U. Giostra, L. Buligon, G. A. Degrazia, D. Cava
Summary: This study investigates the influence of coherent vortices on turbulence structure above and below a dense plant canopy. Turbulence measurements collected at different levels within a coniferous forest on an Alpine Plateau were analyzed. The results show that the dominant time scale of momentum flux is mainly determined by the longitudinal wind velocity component under near-neutral conditions. In free convection and very stable conditions, the momentum transport is not influenced by coherent vortices generated at the canopy top.
AGRICULTURAL AND FOREST METEOROLOGY
(2023)
Article
Mechanics
O. Ozcakir, P. Hall, H. M. Blackburn
Summary: The linear instability of flow in a pipe with wavelike transpiration velocity at the walls is analyzed. High Reynolds numbers and small transpiration velocities are considered in the formulation of the fully nonlinear problem. Solutions of the nonlinear system that describe the bifurcation of disturbances resulting from transpiration are calculated, revealing a complex bifurcation structure with multiple possible nonlinear states at certain levels of transpiration amplitude. The symmetries and structure of the nonlinear solutions are discussed.
JOURNAL OF FLUID MECHANICS
(2022)
Article
Physics, Multidisciplinary
V Pineda-Reyes, L. F. Escamilla-Herrera, C. Gruber, F. Nettel, H. Quevedo
Summary: This study investigates the consequences of reparameterizations on the geometric description of thermodynamics and finds that they can be coded in the contact and Riemannian structures of the thermodynamic phase space. Even though the geometric structures are modified by the reparameterizations, the metric structure on the thermodynamic equilibrium space is preserved.
PHYSICA A-STATISTICAL MECHANICS AND ITS APPLICATIONS
(2021)
Article
Mechanics
Valentina Valori, Alessio Innocenti, Berengere Dubrulle, Sergio Chibbaro
JOURNAL OF FLUID MECHANICS
(2020)
Article
Physics, Multidisciplinary
V Labarre, B. Dubrulle, D. Paillard
JOURNAL OF PHYSICS A-MATHEMATICAL AND THEORETICAL
(2020)
Article
Physics, Fluids & Plasmas
Zecong Qin, Hugues Faller, Berengere Dubrulle, Aurore Naso, Wouter J. T. Bos
PHYSICAL REVIEW FLUIDS
(2020)
Article
Physics, Multidisciplinary
Vincent Labarre, Didier Paillard, Berengere Dubrulle
Article
Computer Science, Interdisciplinary Applications
L. Cappanera, P. Debue, H. Faller, D. Kuzzay, E-W Saw, C. Nore, J-L Guermond, F. Daviaud, C. Wiertel-Gasquet, B. Dubrulle
Summary: This paper investigates the comparison between experimental, direct numerical simulation (DNS), and large eddy simulation (LES) results in a von Karman flow, where two counter-rotating impellers are driving the fluid in a cylindrical container. The study validates the proposed LES model and demonstrates a high level of agreement between numerical and experimental data, indicating that each technique can be used with high confidence to explore and understand turbulence in complex flows at Reynolds numbers of O(10^5) and beyond.
COMPUTERS & FLUIDS
(2021)
Article
Mechanics
H. Faller, D. Geneste, T. Chaabo, A. Cheminet, V. Valori, Y. Ostovan, L. Cappanera, Ch. Cuvier, F. Daviaud, J. -M. Foucaut, J. -L. Guermond, J. -Ph. Laval, C. Nore, V. Padilla, C. Wiertel, B. Dubrulle
Summary: Through numerical and experimental data, the study finds that the structure functions of small scale turbulence exhibit a generalized extended scaling and have consistent multi-fractal spectra, supporting a local refined hypothesis. Both areas of strong vorticity and strong local energy transfer show high intermittency and correlation. In the shear layer, there is a stronger correlation between vorticity and local energy transfer, possibly indicating a self-similar quasi-singular structure dominating the scaling properties of large order structure functions.
JOURNAL OF FLUID MECHANICS
(2021)
Article
Mechanics
P. Debue, V. Valori, C. Cuvier, F. Daviaud, J. -M. Foucaut, J. -P. Laval, C. Wiertel, V. Padilla, B. Dubrulle
Summary: By studying the three-dimensional structure of turbulent velocity fields around extreme events of local energy transfer in the dissipative range, it was found that most extreme events of local energy transfer correspond to the vortex stretching topology, with large velocity and vorticity norms, and the structure of the vorticity field around these events agrees with previous observations.
JOURNAL OF FLUID MECHANICS
(2021)
Article
Thermodynamics
Adam Cheminet, Yasar Ostovan, Valentina Valori, Christophe Cuvier, Fancois Daviaud, Paul Debue, Berengere Dubrulle, Jean-Marc Foucaut, Jean-Philippe Laval
Summary: The study investigates denoising of Lagrangian trajectories using regularized B-spline and introduces innovative tuning strategies to optimize algorithms for 4D-PTV measurements of turbulent flows. The strategies are found to be more adaptable to real experimental noise compared to conventional methods after testing on synthetic trajectories and experimental data.
EXPERIMENTAL THERMAL AND FLUID SCIENCE
(2021)
Article
Physics, Multidisciplinary
Simon Thalabard, Sergey Medvedev, Vladimir Grebenev, Sergey Nazarenko
Summary: In this paper, we analyze a family of fourth-order non-linear diffusion models which correspond to local approximations of four-wave kinetic equations of weak wave turbulence. We focus on a class of parameters where a dual cascade behavior is expected, associated with an infrared finite-time singularity related to inverse transfer of waveaction. This case is relevant for wave turbulence in the nonlinear Schrodinger model and gravitational waves in the Einstein's vacuum field model. We show that the inverse transfer is not described by a scaling of the constant-flux solution but has an anomalous scaling. We compute the anomalous exponents and analyze their origin using the theory of dynamical systems.
JOURNAL OF PHYSICS A-MATHEMATICAL AND THEORETICAL
(2022)
Article
Multidisciplinary Sciences
Alexei A. Mailybaev, Simon Thalabard
Summary: This article reveals a hidden scaling symmetry of the Navier-Stokes equations in the limit of vanishing viscosity. Through dynamical space-time rescaling, this symmetry projects solutions that differ only up to Galilean invariance and global temporal scaling onto the same representative flow. This symmetry statistically repairs the broken scale invariance caused by intermittency in the original formulation.
PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY A-MATHEMATICAL PHYSICAL AND ENGINEERING SCIENCES
(2022)
Article
Chemistry, Physical
Brice Saint-Michel, George Petekidis, Valeria Garbin
Summary: The dynamics of a deformable inclusion, such as a bubble, can be used to locally tune the microstructure of a colloidal gel. Bubble dissolution leads to the formation of a solvent pocket, while ultrasound-induced bubble oscillations rearrange the gel particles into a microstructure with increased local ordering.
Article
Physics, Multidisciplinary
Hugues Faller, Lucas Fery, Damien Geneste, Berengere Dubrulle
Summary: We introduce a model of interacting singularities of Navier-Stokes equations, named pincons. This model can be seen as a generalization of the vorton model of Novikov that was derived for the Euler equations. The pincons exhibit self-motion and can maintain a non-equilibrium state under certain conditions.
Review
Mathematics, Interdisciplinary Applications
Berengere Dubrulle
Summary: Kolmogorov's theory explains the hierarchical organization of vortices and the universal energy spectrum observed in turbulent flows. However, finer observations reveal intermittency and high velocity derivatives, which can be explained using the concept of multi-fractality.
FRACTAL AND FRACTIONAL
(2022)
Review
Geosciences, Multidisciplinary
Berengere Dubrulle, Francois Daviaud, Davide Faranda, Louis Marie, Brice Saint-Michel
Summary: This article explores the scientific admissibility of climate projections and predictions, focusing on transitions between metastable states in atmospheric and oceanic circulations. By examining climate models' ability to replicate spontaneous or forced transitions in weather patterns, the study draws an analogy to laboratory-scale turbulent flows. Factors such as the nature of transitions, degrees of freedom, and the role of fluctuations are investigated, emphasizing the importance of accurately capturing small-scale fluctuations.
NONLINEAR PROCESSES IN GEOPHYSICS
(2022)
Article
Physics, Fluids & Plasmas
F. Nguyen, J-P Laval, B. Dubrulle
