Lagrangian observations and modelling of turbulence along a tidally influenced river

2021 ◽  
Author(s):  
Bérengère S. Dejeans ◽  
Julia C. Mullarney ◽  
Iain T. MacDonald
Keyword(s):  
Lagrangian Observations

Enhanced Predictability Through Lagrangian Observations and Analysis

2007 ◽  
Author(s):  
Jr Lipphardt ◽  
Kirwan B. L. ◽  
A. D. Jr
Keyword(s):  
Lagrangian Observations

scholarly journals Interaction of Superinertial Waves with Submesoscale Cyclonic Filaments in the North Wall of the Gulf Stream

2018 ◽  
Vol 48 (1) ◽  
pp. 81-99 ◽  
Author(s):  
Daniel B. Whitt ◽  
Leif N. Thomas ◽  
Jody M. Klymak ◽  
Craig M. Lee ◽  
Eric A. D’Asaro
Keyword(s):  
Wave Propagation ◽  
Gulf Stream ◽  
Vertical Shear ◽  
Vertical Vorticity ◽  
Shear Structures ◽  
The North ◽  
Lagrangian Observations ◽  
Critical Layers ◽  
Balanced Flow ◽  
North Wall

AbstractHigh-resolution, nearly Lagrangian observations of velocity and density made in the North Wall of the Gulf Stream reveal banded shear structures characteristic of near-inertial waves (NIWs). Here, the current follows submesoscale dynamics, with Rossby and Richardson numbers near one, and the vertical vorticity is positive. This allows for a unique analysis of the interaction of NIWs with a submesoscale current dominated by cyclonic as opposed to anticyclonic vorticity. Rotary spectra reveal that the vertical shear vector rotates primarily clockwise with depth and with time at frequencies near and above the local Coriolis frequency f. At some depths, more than half of the measured shear variance is explained by clockwise rotary motions with frequencies between f and 1.7f. The dominant superinertial frequencies are consistent with those inferred from a dispersion relation for NIWs in submesoscale currents that depends on the observed aspect ratio of the wave shear as well as the vertical vorticity, baroclinicity, and stratification of the balanced flow. These observations motivate a ray tracing calculation of superinertial wave propagation in the North Wall, where multiple filaments of strong cyclonic vorticity strongly modify wave propagation. The calculation shows that the minimum permissible frequency for inertia–gravity waves is mostly greater than the Coriolis frequency, and superinertial waves can be trapped and amplified at slantwise critical layers between cyclonic vortex filaments, providing a new plausible explanation for why the observed shear variance is dominated by superinertial waves.

Lagrangian observations of an anticyclonic ring in the western Gulf of Mexico

1984 ◽  
Vol 89 (C3) ◽  
pp. 3417 ◽  
Author(s):  
A. D. Kirwan ◽  
W. J. Merrell ◽  
J. K. Lewis ◽  
R. E. Whitaker
Keyword(s):  
Gulf Of Mexico ◽  
Lagrangian Observations

Capturing eddy shedding in the Gulf of Mexico from Lagrangian observations

2011 ◽  
Vol 240 (2) ◽  
pp. 166-179 ◽  
Author(s):  
Guillaume Vernieres ◽  
Christopher K.R.T. Jones ◽  
Kayo Ide
Keyword(s):  
Gulf Of Mexico ◽  
Lagrangian Observations ◽  
Eddy Shedding

scholarly journals Development and Evaluation of an Autonomous Sensor for the Observation of Sediment Motion*

2014 ◽  
Vol 31 (4) ◽  
pp. 1012-1019 ◽  
Author(s):  
Donya Frank ◽  
Diane Foster ◽  
Pai Chou ◽  
Yu-Min Kao ◽  
In Mei Sou ◽  
...  
Keyword(s):  
High Speed ◽  
Coastal Sediments ◽  
Angle Of Repose ◽  
Incipient Motion ◽  
Stress Criterion ◽  
Video Cameras ◽  
Mobile Bed ◽  
Autonomous Sensor ◽  
Lagrangian Observations ◽  
Lagrangian Measurements

Abstract Measurements within the mobile bed layer have been limited by previous Eulerian-based technologies. A microelectromechanical system device, called a smart sediment grain (SSG), that can measure and record Lagrangian observations of coastal sediments at incipient motion has been developed. These sensors have the potential to resolve fundamental hypotheses regarding the incipient motion of coastal sediments. Angle of repose experiments verified that the sensor enclosure has mobility characteristics similar to coarse gravel. Experiments conducted in a small oscillating flow tunnel verified that the sensors detect incipient motion under various hydrodynamic conditions. Evidence suggests the influence of pressure-gradient-induced sediment motion, contrary to the more commonly assumed bed shear stress criterion. Lagrangian measurements of rotation measured with the newly developed SSG agreed to within 5% of the rotation estimates made simultaneously with high-speed video cameras.

Lagrangian observations of homogeneous random environments

2001 ◽  
Vol 33 (4) ◽  
pp. 810-835 ◽  
Author(s):  
Craig L. Zirbel
Keyword(s):  
Velocity Field ◽  
Molecular Diffusion ◽  
Physical Space ◽  
Flow Property ◽  
Random Environments ◽  
Unified Framework ◽  
Random Mappings ◽  
Lagrangian Observations ◽  
Random Location ◽  
Strictly Stationary Process

This article deals with the distribution of the view of a random environment as seen by an observer whose location at each moment is determined by the environment. The main application is in statistical fluid mechanics, where the environment consists of a random velocity field and the observer is a particle moving in the velocity field, possibly subject to molecular diffusion. Several results on such Lagrangian observations of the environment have appeared in the literature, beginning with the 1957 dissertation of J. L. Lumley. This article unites these results into a simple unified framework and rounds out the theory with new results in several directions. When the environment is homogeneous, the problem can be re-cast in terms of certain random mappings on the physical space that are based on the random location of the observer. If these mappings preserve the invariant measure on the physical space, then the view from the random location has the same distribution as the view from the origin. If these mappings satisfy the flow property and the environment is stationary, then the succession of Lagrangian observations over time forms a strictly stationary process. In particular, for motion in a homogeneous, stationary, and nondivergent velocity field, the Lagrangian velocity (the velocity of the particle) is strictly stationary, which was first observed by Lumley. In the compressible case, the distribution of a Lagrangian observation has a density with respect to the distribution of the view from the origin, and in some cases convergence in distribution of the Lagrangian observations as time tends to infinity can be shown.

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