English
norskBlar i forfatter Artikler, rapporter og annet (matematikk og statistikk) "Aksamit, Nikolas Olson"
Viser treff 1-4 av 4
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Interplay between advective, diffusive and active barriers in (rotating) Rayleigh-Bénard flow
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-08-22)Our understanding of the material organization of complex fluid flows has benefited recently from mathematical developments in the theory of objective coherent structures. These methods have provided a wealth of approaches that identify transport barriers in three-dimensional (3-D) turbulent flows. Specifically, theoretical advances have been incorporated into numerical algorithms that extract ... -
Mapping the shape and dimension of three-dimensional Lagrangian coherent structures and invariant manifolds
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-03-10)We introduce maps of Cauchy–Green strain tensor eigenvalues to barycentric coordinates to quantify and visualize the full geometry of three-dimensional deformation in stationary and non-stationary fluid flows. As a natural extension of Lagrangian coherent structure diagnostics, which provide separate scalar fields and a one-dimensional quantification of fluid deformation, our barycentric mapping ... -
Objective Momentum Barriers in Wall Turbulence
(Journal article; Tidsskriftartikkel; Peer reviewed, 2022-04-28)We use the recent frame-indifferent theory of diffusive momentum transport to identify internal barriers in wall-bounded turbulence. Formed by the invariant manifolds of the Laplacian of the velocity field, the barriers block the viscous part of the instantaneous momentum flux in the flow. We employ the level sets of single-trajectory Lagrangian diagnostic tools, the trajectory rotation average ... -
A quasi-objective single buoy approach for un- derstanding Lagrangian coherent structures and sea ice dynamics
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-04-11)Sea ice drift and deformation, namely sea ice dynamics, play a significant role in atmosphere–ice–ocean coupling. Deformation patterns in sea ice can be observed over a wide range of spatial and temporal scales, though high-resolution objective quantification of these features remains difficult. In an effort to better understand local deformation of sea ice, we adapt the trajectory-stretching exponents ...
