Lagrangian coherent structures
View article
Submesoscale currents in the ocean Open
This article is a perspective on the recently discovered realm of submesoscale currents in the ocean. They are intermediate-scale flow structures in the form of density fronts and filaments, topographic wakes and persistent coherent vortic…
View article
Coherent structures in wall-bounded turbulence Open
This article discusses the description of wall-bounded turbulence as a deterministic high-dimensional dynamical system of interacting coherent structures, defined as eddies with enough internal dynamics to behave relatively autonomously fr…
View article
A critical comparison of Lagrangian methods for coherent structure detection Open
We review and test twelve different approaches to the detection of finite-time coherent material structures in two-dimensional, temporally aperiodic flows. We consider both mathematical methods and diagnostic scalar fields, comparing their…
View article
Spectral-clustering approach to Lagrangian vortex detection Open
One of the ubiquitous features of real-life turbulent flows is the existence and persistence of coherent vortices. Here we show that such coherent vortices can be extracted as clusters of Lagrangian trajectories. We carry out the clusterin…
View article
Flow structures in transitional and turbulent boundary layers Open
The basic problems of transition in both incompressible and compressible boundary layers are reviewed. Flow structures in low-speed transitional and developed turbulent boundary layers are presented, together with almost all of the physica…
View article
Exact Coherent States and the Nonlinear Dynamics of Wall-Bounded Turbulent Flows Open
Wall-bounded turbulence exhibits patterns that persist in time and space: coherent structures. These are important for transport processes and form a conceptual framework for important theoretical approaches. Key observed structures includ…
View article
Fluid theory and simulations of instabilities, turbulent transport and coherent structures in partially-magnetized plasmas of $\mathbf{E}\times \mathbf{B}$ discharges Open
Partially-magnetized plasmas with magnetized electrons and non-magnetized ions are common in Hall thrusters for electric propulsion and magnetron material processing devices. These plasmas are usually in strongly non-equilibrium state due …
View article
Lagrangian based methods for coherent structure detection Open
There has been a proliferation in the development of Lagrangian analytical methods for detecting coherent structures in fluid flow transport, yielding a variety of qualitatively different approaches. We present a review of four approaches …
View article
Electron vortex magnetic holes: A nonlinear coherent plasma structure Open
We report the properties of a novel type of sub-proton scale magnetic hole found in two dimensional particle-in-cell simulations of decaying turbulence with a guide field. The simulations were performed with a realistic value for ion to el…
View article
Confined Rayleigh-Bénard, Rotating Rayleigh-Bénard, and Double Diffusive Convection: A Unifying View on Turbulent Transport Enhancement through Coherent Structure Manipulation Open
Many natural and engineering systems are simultaneously subjected to a driving force and a stabilizing force. The interplay between the two forces, especially for highly nonlinear systems such as fluid flow, often results in surprising fea…
View article
Spectral proper orthogonal decomposition and resolvent analysis of near-wall coherent structures in turbulent pipe flows Open
View article
Lagrangian coherent structures in the flow field of a fluidic oscillator Open
This paper is associated with a video winner of a 2015 APS/DFD Gallery of Fluid Motion Award. The original video is available from the Gallery of Fluid Motion, http://dx.doi.org/10.1103/APS.DFD.2015.GFM.V0015
View article
Coherent Lagrangian swirls among submesoscale motions Open
Significance The detection of vortices in geophysical flows is important because of their role in global circulation and transport. The recent theory of elliptic Lagrangian coherent structures has shown that long-lived, coherent material e…
View article
Coherent structures in wall-bounded turbulence Open
The inherent difficulty of understanding turbulence has led to researchers attacking the topic in many different ways over the years of turbulence research. Some approaches have been more successful than others, but most only deal with par…
View article
Forecasting Fluid Flows Using the Geometry of Turbulence Open
The existence and dynamical role of particular unstable solutions (exact coherent structures) of the Navier-Stokes equation is revealed in laboratory studies of weak turbulence in a thin, electromagnetically driven fluid layer. We find tha…
View article
Coordinated Unmanned Aircraft System (UAS) and Ground-Based Weather Measurements to Predict Lagrangian Coherent Structures (LCSs) Open
Concentrations of airborne chemical and biological agents from a hazardous release are not spread uniformly. Instead, there are regions of higher concentration, in part due to local atmospheric flow conditions which can attract agents. We …
View article
Structure of coherent vortices generated by the inverse cascade of two-dimensional turbulence in a finite box Open
We discuss the structure and geometrical characteristics of coherent vortices appearing as a result of the inverse cascade in two-dimensional turbulence in a finite box. We demonstrate that the universal velocity profile, established by J.…
View article
First coherent structure in elasto-inertial turbulence Open
Two-dimensional channel flow simulations of FENE-P (finitely extensible nonlinear elastic-Peterlin) fluid in the elasto-inertial turbulence (EIT) regime reveal distinct regimes ranging from chaos to a steady traveling wave which takes the …
View article
Layer formation in horizontally forced stratified turbulence: connecting exact coherent structures to linear instabilities Open
We consider turbulence in a stratified ‘Kolmogorov’ flow, driven by horizontal shear in the form of sinusoidal body forcing in the presence of an imposed background linear stable stratification in the third direction. This flow configurati…
View article
Flowtrace: simple visualization of coherent structures in biological fluid flows Open
We present a simple, intuitive algorithm for visualizing time-varying flow fields that can reveal complex flow structures with minimal user intervention. We apply this technique to a variety of biological systems, including the swimming cu…
View article
Tuning heat transport via coherent structure manipulation: recent advances in thermal turbulence Open
Tuning transport properties through the manipulation of elementary structures has achieved great success in many areas, such as condensed matter physics. However, the ability to manipulate coherent structures in turbulent flows is much les…
View article
Logarithmic-layer turbulence: A view from the wall Open
The observability of the flow field away from the wall in turbulent channel\nflow is studied using only wall observations. Reconstructions are generated\nfrom noiseless but limited wall data using linear stochastic estimation, with\nemphas…
View article
Confinement-Induced Self-Pumping in 3D Active Fluids Open
Two dimensional active fluids display a transition from turbulent to coherent flow upon decreasing the size of the confining geometry. A recent experiment suggests that the behavior in three dimensions is remarkably different; emergent flo…
View article
Exchange Processes Induced by Large Horizontal Coherent Structures in Floodplain Vegetated Channels Open
Mangrove forests along the Mekong delta estuaries are usually observed to degrade together with the increasing extension of fish farms. In this limited‐width condition, the formation of coherent structures, their interactions with mangrove…
View article
Hierarchy of coherent structures and real-space energy transfer in turbulent channel flow Open
View article
The coherent structure of the kinetic energy transfer in shear turbulence Open
The cascade of energy in turbulent flows, i.e., the transfer of kinetic\nenergy from large to small flow scales or vice versa (backward cascade), is the\ncornerstone of most theories and models of turbulence since the 1940s. Yet,\nundersta…
View article
Reduced description of exact coherent states in parallel shear flows Open
A reduced description of exact coherent structures in the transition regime of plane parallel shear flows is developed, based on the Reynolds number scaling of streamwise-averaged (mean) and streamwise-varying (fluctuation) velocities obse…
View article
Dominant transport pathways in an atmospheric blocking event Open
A Lagrangian flow network is constructed for the atmospheric blocking of Eastern Europe and Western Russia in summer 2010. We compute the most probable paths followed by fluid particles, which reveal the Omega-block skeleton of the event. …
View article
Strings of droplets propelled by coherent waves Open
Bouncing walking droplets possess fascinating properties due to their peculiar wave-particle interaction leading to unexpected quantumlike behaviors. We propose a study consisting in droplets walking along annular cavities. We show that, i…
View article
The Scale Characteristics and Formation Mechanism of Aeolian Sand Streamers Based on Large Eddy Simulation Open
Aeolian sand transport near the surface in the field often occurs in the form of sand streamers, which is very important to understand in‐depth the physics of aeolian transport and accurately predict the sand transport rate. In this paper,…