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FTLE (Finite Time Lyapunov Exponent) computation is one of the standard approaches to Lagrangian flow analysis. The main features of interest in FTLE fields are ridges that represent hyperbolic Lagrangian Coherent Structures. FTLE ridges…

Fluid Dynamics · Physics 2024-01-10 Janos Zimmermann , Michael Motejat , Christian Rössl , Holger Theisel

Lagrangian coherent structures (LCS) in fluid flows appear as co-dimension one ridges of the finite time Lyapunov exponent (FTLE) field. In three- dimensions this means two-dimensional ridges. A fast algorithm is presented here to locate…

Fluid Dynamics · Physics 2012-02-24 Doug Lipinski , Kamran Mohseni

Lagrangian techniques, such as the finite-time Lyapunov exponent (FTLE) and hyperbolic Lagrangian coherent structures (LCS), have become popular tools for analyzing unsteady fluid flows. These techniques identify regions where particles…

Chaotic Dynamics · Physics 2020-10-27 Peter J. Nolan , Mattia Serra , Shane D. Ross

This paper compares the advantages, limitations, and computational considerations of using Finite-Time Lyapunov Exponents (FTLEs) and Lagrangian Descriptors (LDs) as tools for identifying barriers and mechanisms of fluid transport in…

Fluid Dynamics · Physics 2021-03-30 Timothy Getscher

We use finite-time Lyapunov exponent (FTLE) distributions to probe transition mechanisms in high-dimensional reservoir maps trained on low-dimensional chaotic dynamics across multiple regimes. While trained reservoirs accurately predict…

Chaotic Dynamics · Physics 2026-04-28 Dishant Sisodia , Sarika Jalan

High-accuracy and high-efficiency finite-time Lyapunov exponent (FTLE) calculation method has long been a research hot point, and adaptive refinement method is a kind of method in this field. The proposed objective-adaptive refinement (OAR)…

Fluid Dynamics · Physics 2021-04-27 Haotian Hang , Bin Yu , Yang Xiang , Bin Zhang , Hong Liu

Finite-time Lyapunov exponents (FTLEs) provide a powerful approach to compute time-varying analogs of invariant manifolds in unsteady fluid flow fields. These manifolds are useful to visualize the transport mechanisms of passive tracers…

Optimization and Control · Mathematics 2023-05-19 Kartik Krishna , Steven L. Brunton , Zhuoyuan Song

In this paper we use the finite size Lyapunov Exponent (FSLE) to characterize Lagrangian coherent structures in three-dimensional (3d) turbulent flows. Lagrangian coherent structures act as the organizers of transport in fluid flows and are…

Chaotic Dynamics · Physics 2013-06-12 João H Bettencourt , Cristóbal López , Emilio Hernández-García

We review and discuss some different techniques for describing local dispersion properties in fluids. A recent Lagrangian diagnostics, based on the Finite Scale Lyapunov Exponent (FSLE), is presented and compared to the Finite Time Lyapunov…

Chaotic Dynamics · Physics 2009-11-07 G. Boffetta , G. Lacorata , G. Redaelli , A. Vulpiani

The identification and visualization of Lagrangian structures in flows plays a crucial role in the study of dynamic systems and fluid dynamics. The Finite Time Lyapunov Exponent (FTLE) has been widely used for this purpose; however, it only…

Dynamical Systems · Mathematics 2024-01-18 Yun Chen Tsai , Shingyu Leung

We propose a new Eulerian numerical approach for constructing the forward flow maps in continuous dynamical systems. The new algorithm improves the original formulation developed in [23, 24] so that the associated partial differential…

Dynamical Systems · Mathematics 2017-06-15 Guoqiao You , Tony Wong , Shingyu Leung

The problem of phase space transport which is of interest both theoretically and from the point of view of applications has been investigated extensively using geometric and probabilistic methods. Two of the important tools for this that…

Chaotic Dynamics · Physics 2011-07-06 Phanindra Tallapragada

In this work we investigate the dynamics of inertial particles using finite-time Lyapunov exponents (FTLE). In particular, we characterize the attractor and repeller structures underlying preferential concentration of inertial particles in…

Fluid Dynamics · Physics 2016-03-23 M. Sudharsan , Steven L. Brunton , James J. Riley

In the context of the analysis of the chaotic properties of homogeneous and isotropic turbulence, direct numerical simulations are used to study the fluctuations of the finite time Lyapunov exponent (FTLE) and its relation to Reynolds…

Fluid Dynamics · Physics 2020-02-19 Richard Ho , Andres Armua , Arjun Berera

Much of atmospheric and oceanic transport is associated with coherent structures. Lagrangian methods are emerging as optimal tools for their identification and analysis. An important Lagrangian technique which is starting to be widely used…

We consider issues associated with the Lagrangian characterisation of flow structures arising in aperiodically time-dependent vector fields that are only known on a finite time interval. A major motivation for the consideration of this…

Chaotic Dynamics · Physics 2020-01-29 Michal Branicki , Stephen Wiggins

Ridges of the Finite-Size Lyapunov Exponent (FSLE) field have been used as indicators of hyperbolic Lagrangian Coherent Structures (LCSs). A rigorous mathematical link between the FSLE and LCSs, however, has been missing. Here we prove that…

Dynamical Systems · Mathematics 2014-01-14 Daniel Karrasch , George Haller

This work provides an experimental method for simultaneously measuring finite time Lyapunov exponent fields for multiple particle groups, including non-flow tracers, in three-dimensional multiphase flows. From sequences of particle images,…

Fluid Dynamics · Physics 2013-10-07 Samuel G. Raben , Shane D. Ross , Pavlos P. Vlachos

It is a wide-spread convention to identify repelling Lagrangian Coherent Structures (LCSs) with ridges of the forward finite-time Lyapunov exponent (FTLE) field, and attracting LCSs with ridges of the backward FTLE. We show that in…

Dynamical Systems · Mathematics 2019-01-29 Daniel Karrasch

The dynamics of inertial particles in fluid flows have been the focus of extensive research due to their relevance in a wide range of industrial and environmental processes. Earlier studies have examined the dynamics of aerosols and bubbles…

Fluid Dynamics · Physics 2024-09-05 P. Swaathi , Sanjit Das , N. Nirmal Thyagu
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