scholarly journals Automated detection of coherent Lagrangian vortices in two-dimensional unsteady flows

2015 ◽  
Vol 471 (2173) ◽  
pp. 20140639 ◽  
Author(s):  
Daniel Karrasch ◽  
Florian Huhn ◽  
George Haller
Keyword(s):  
Satellite Altimetry ◽  
Large Scale ◽  
Strain Tensor ◽  
Unsteady Flows ◽  
Fluid Flows ◽  
Ocean Surface ◽  
Automated Detection ◽  
Two Dimensional ◽  
Green Strain ◽  
Closed Orbits

Coherent boundaries of Lagrangian vortices in fluid flows have recently been identified as closed orbits of line fields associated with the Cauchy–Green strain tensor. Here, we develop a fully automated procedure for the detection of such closed orbits in large-scale velocity datasets. We illustrate the power of our method on ocean surface velocities derived from satellite altimetry.

Detection of large-scale ocean circulation and tides

1983 ◽  
Vol 309 (1508) ◽  
pp. 361-370 ◽  
Keyword(s):  
Heat Flux ◽  
Surface Topography ◽  
Ocean Circulation ◽  
Satellite Altimetry ◽  
Large Scale ◽  
Precise Measurement ◽  
Ocean Surface ◽  
Ocean Topography ◽  
Tidal Signal ◽  
Nearly Continuous

As emphasized recently by Munk & Wunsch, the traditional methods of monitoring the ocean circulation give data too hopelessly aliased in space and time to permit a proper assessment of basin-wide dynamics and heat flux on climatic timescales. The prospect of nearly continuous recording of ocean-surface topography by satellite altimetry with suitable supporting measurements might make such assessments possible. The associated identification of the geocentric oceanic tidal signal in the data would be an additional bonus. The few weeks of altimetry recorded by Seasat gave a glimpse of the possibilities, but also clarified the areas where better precision and knowledge are needed. Further experience will be gained from currently projected multi-purpose satellites carrying altimeters, but serious knowledge of ocean circulation will result only from missions that are entirely dedicated to the precise measurement of ocean topography.

scholarly journals Alignment of vorticity and rods with Lagrangian fluid stretching in turbulence

2014 ◽  
Vol 743 ◽  
Author(s):  
Rui Ni ◽  
Nicholas T. Ouellette ◽  
Greg A. Voth
Keyword(s):  
Isotropic Turbulence ◽  
Strain Tensor ◽  
Fluid Flows ◽  
Strain Rate Tensor ◽  
Eulerian Strain ◽  
Green Strain ◽  
Material Element ◽  
Strain Tensors ◽  
Strong Vorticity ◽  
Preferential Alignment

AbstractStretching in continuum mechanics is naturally described using the Cauchy–Green strain tensors. These tensors quantify the Lagrangian stretching experienced by a material element, and provide a powerful way to study processes in turbulent fluid flows that involve stretching such as vortex stretching and alignment of anisotropic particles. Analysing data from a simulation of isotropic turbulence, we observe preferential alignment between rods and vorticity. We show that this alignment arises because both of these quantities independently tend to align with the strongest Lagrangian stretching direction, as defined by the maximum eigenvector of the left Cauchy–Green strain tensor. In particular, rods approach almost perfect alignment with the strongest stretching direction. The alignment of vorticity with stretching is weaker, but still much stronger than previously observed alignment of vorticity with the eigenvectors of the Eulerian strain rate tensor. The alignment of strong vorticity is almost the same as that of rods that have experienced the same stretching.

Thin structure of heterogeneous and multiphase fluid flows

2012 ◽  
Vol 9 (1) ◽  
pp. 175-180
Author(s):  
Yu.D. Chashechkin
Keyword(s):  
Large Scale ◽  
Fundamental System ◽  
Fluid Flows ◽  
Regular Solutions ◽  
Flow Models ◽  
Group Methods ◽  
Wide Range ◽  
Thin Structure ◽  
Multiphase Fluid ◽  
Complete Solutions

According to the results of visualization of streams, the existence of structures in a wide range of scales is noted: from galactic to micron. The use of a fundamental system of equations is substantiated based on the results of comparing symmetries of various flow models with the usage of theoretical group methods. Complete solutions of the system are found by the methods of the singular perturbations theory with a condition of compatibility, which determines the characteristic equation. A comparison of complete solutions with experimental data shows that regular solutions characterize large-scale components of the flow, a rich family of singular solutions describes formation of the thin media structure. Examples of calculations and observations of stratified, rotating and multiphase media are given. The requirements for the technique of an adequate experiment are discussed.

Solution‐Processed Large‐Scale Concentric‐Ring Laser on Two‐Dimensional Ruddlesden–Popper Perovskites Thin Films

2021 ◽  
pp. 2100193
Author(s):  
Peng Liu ◽  
Bingqian Zhang ◽  
Qing Liao ◽  
Guifen Tian ◽  
Chunling Gu ◽  
...  
Keyword(s):  
Thin Films ◽  
Ring Laser ◽  
Large Scale ◽  
Two Dimensional ◽  
Concentric Ring ◽  
Solution Processed

Large-scale visualization of dispersion of liquid-exfoliated two-dimensional nanosheets

2021 ◽  
Author(s):  
Xingyu Cui ◽  
Wen ying Shi ◽  
Chao Lu
Keyword(s):  
Aqueous Solution ◽  
Large Scale ◽  
Fluorescence Microscope ◽  
Visualization Method ◽  
Two Dimensional ◽  
Non Invasive

An ultrafast, non-invasive and large-scale visualization method has been developed to evaluate the dispersion of two-dimensional nanosheets in aqueous solution with fluorescence microscope by formation of excimers from improvement of...

scholarly journals Universality class of the motility-induced critical point in large scale off-lattice simulations of active particles.

Soft Matter ◽  
2021 ◽  
Author(s):  
Claudio Maggi ◽  
Matteo Paoluzzi ◽  
Andrea Crisanti ◽  
Emanuela Zaccarelli ◽  
Nicoletta Gnan
Keyword(s):  
Phase Separation ◽  
Critical Point ◽  
Computer Simulations ◽  
Large Scale ◽  
Universality Class ◽  
Critical Behaviour ◽  
Two Dimensional ◽  
Dimensional Model ◽  
Active Particles ◽  
Two Dimensional Model

We perform large-scale computer simulations of an off-lattice two-dimensional model of active particles undergoing a motility-induced phase separation (MIPS) to investigate the systems critical behaviour close to the critical point...

Unusually High Ion Conductivity in Large-Scale Patternable Two-Dimensional MoS2 Film

ACS Nano ◽  
2021 ◽  
Author(s):  
Juhong Park ◽  
Sanket Bhoyate ◽  
Young-Hoon Kim ◽  
Young-Min Kim ◽  
Young Hee Lee ◽  
...  
Keyword(s):  
Large Scale ◽  
Ion Conductivity ◽  
Two Dimensional ◽  
Mos2 Film
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