Étude Lagrangienne D'une Turbulence Inhomogène

Étude Lagrangienne D'une Turbulence Inhomogène PDF Author: Nickolas Stelzenmuller
Publisher:
ISBN:
Category :
Languages : en
Pages : 0

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Book Description
Inhomogeneous turbulence is experimentally investigated in a Lagrangian framework. Measurements of tracer and non-tracer particles in a turbulent channel were made, and were used to extract Lagrangian statistics conditioned on their initial distance to the channel wall. Highly resolved in time and space, these measurements provide the three components of position, velocity, and acceleration along a particle trajectory from very close to the channel wall (approx 10) to the channel center. Lagrangian time correlations allow the direct measurement of velocity and acceleration timescales in each direction, and characterize the inhomogeneity and anisotropy of the turbulent channel from the Lagrangian perspective. Small scale-anisotropy, characterized by the skewness and the correlation of the components of the acceleration, was found to be significant throughout the channel. Significant scale separation between the magnitude and components of acceleration was found across the channel, even in the near-wall region. Two classes of non-tracer particle trajectories were also measured, allowing direct comparison of tracer and non-tracer statistics from the highly-sheared anisotropic zone near the channel wall to the more homogeneous outer layer. Non-tracer acceleration statistics in the turbulent channel were found to be significantly different from similar results in homogeneous, isotropic turbulence. These statistics are necessary components of advanced Lagrangian stochastic models to predict dispersion and mixing in inhomogeneous turbulence.

Étude Lagrangienne D'une Turbulence Inhomogène

Étude Lagrangienne D'une Turbulence Inhomogène PDF Author: Nickolas Stelzenmuller
Publisher:
ISBN:
Category :
Languages : en
Pages : 0

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Book Description
Inhomogeneous turbulence is experimentally investigated in a Lagrangian framework. Measurements of tracer and non-tracer particles in a turbulent channel were made, and were used to extract Lagrangian statistics conditioned on their initial distance to the channel wall. Highly resolved in time and space, these measurements provide the three components of position, velocity, and acceleration along a particle trajectory from very close to the channel wall (approx 10) to the channel center. Lagrangian time correlations allow the direct measurement of velocity and acceleration timescales in each direction, and characterize the inhomogeneity and anisotropy of the turbulent channel from the Lagrangian perspective. Small scale-anisotropy, characterized by the skewness and the correlation of the components of the acceleration, was found to be significant throughout the channel. Significant scale separation between the magnitude and components of acceleration was found across the channel, even in the near-wall region. Two classes of non-tracer particle trajectories were also measured, allowing direct comparison of tracer and non-tracer statistics from the highly-sheared anisotropic zone near the channel wall to the more homogeneous outer layer. Non-tracer acceleration statistics in the turbulent channel were found to be significantly different from similar results in homogeneous, isotropic turbulence. These statistics are necessary components of advanced Lagrangian stochastic models to predict dispersion and mixing in inhomogeneous turbulence.

Measuring Ocean Currents

Measuring Ocean Currents PDF Author: Antony Joseph
Publisher: Newnes
ISBN: 0123914280
Category : Science
Languages : en
Pages : 447

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Book Description
Measuring Ocean Currents: Tools, Technologies, and Data covers all major aspects of ocean current measurements in view of the implications of ocean currents on changing climate, increasing pollution levels, and offshore engineering activities. Although more than 70% of the Earth is covered by ocean, there is limited information on the countless fine- to large-scale water motions taking place within them. This book fills that information gap as the first work that summarizes the state-of-the-art methods and instruments used for surface, subsurface, and abyssal ocean current measurements. Readers of this book will find a wealth of information on Lagrangian measurements, horizontal mapping, imaging, Eulerian measurements, and vertical profiling techniques. In addition, the book describes modern technologies for remote measurement of ocean currents and their signatures, including HF Doppler radar systems, satellite-borne sensors, ocean acoustic tomography, and more. Crucial aspects of ocean currents are described in detail as well, including dispersion of effluents discharged into the sea and transport of beneficial materials—as well as environmentally hazardous materials—from one region to another. The book highlights several important practical applications, showing how measurements relate to climate change and pollution levels, how they affect coastal and offshore engineering activities, and how they can aid in tsunami detection. - Coverage of measurement, mapping and profiling techniques - Descriptions of technologies for remote measurement of ocean currents and their signatures - Reviews crucial aspects of ocean currents, including special emphasis on the planet-spanning thermohaline circulation, known as the ocean's "conveyor belt," and its crucial role in climate change

Coastal Acoustic Tomography

Coastal Acoustic Tomography PDF Author: Arata Kaneko
Publisher: Elsevier
ISBN: 0128189428
Category : Science
Languages : en
Pages : 363

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Book Description
Coastal Acoustic Tomography begins with the specifics required for designing a Coastal Acoustic Tomography (CAT) experiment and operating the CAT system in coastal seas. Following sections discuss the procedure for data analyses and various application examples of CAT to coastal/shallow seas (obtained in various locations). These sections are broken down into four kinds of methods: horizontal-slice inversion, vertical-slice inversion, modal expansion method and data assimilation. This book emphasizes how dynamic phenomena occurring in coastal/shallow seas can be analyzed using the standard method of inversion and data assimilation. The book is relevant for physical oceanographers, ocean environmentalists and ocean dynamists, focusing on the event being observed rather than the intrinsic details of observational processes. Application examples of successful dynamic phenomena measured by coastal acoustic tomography are also included. - Provides the information needed for researchers and graduate students in physical oceanography, ocean-fluid dynamics and ocean environments to apply Ocean Acoustic Tomography (OAT) to their own fields - Presents the benefits of using acoustic tomography, including less disturbance to aquatic environments vs. other monitoring methods - Includes the assimilation of CAT data into a coastal sea circulation model, a powerful tool to predict coastal-sea environmental changes

Radar Interferometry

Radar Interferometry PDF Author: Howard Zebker
Publisher: Wiley-Interscience
ISBN: 9780471581109
Category : Technology & Engineering
Languages : en
Pages : 600

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Book Description
This book is the definitive text on the application of interferometric radar techniques to the solution of current geophysical problems, using examples and discoveries from the author's world-famous lab at Stanford University, JPL, NASA, and the Department of Defense. It describes the notation and coordinate systems used within the field, the importance of phase measurements, and provides a brief discussion of the parallel argument for point target scatterers. It also introduces the concept of correlation of radar signals from different antennas, fundamental to the performance of any interferometer.