A Preliminary Field Study of Turbulent Flow Over and Inside a Forest Edge

A Preliminary Field Study of Turbulent Flow Over and Inside a Forest Edge PDF Author: J. D. Lin
Publisher:
ISBN:
Category :
Languages : en
Pages : 116

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Book Description
This study focused on field measurements to determine the spatial variability of the turbulence characteristics under various atmospheric and forest canopy conditions. A high-speed multi-channel data acquisition system was configured and tested. Fixed and movable observation towers have been set up in the University experimental forest in Coventry, Conn. Two wind velocity sensors, being tested and evaluated in the laboratory for their capability to measure the three-dimensional flow with high turbulence intensity that generally characterizes the flow regime in a forest canopy; are a dual triple-split hot-film probe and a tri-diagonal hot-film probe with a wind octant electronic sensor (WOES). The response of WOES tested in the low-speed wind nozzle appears to be promising and its compatibility with the tri-diagonal hot-film probe is being evaluated. A number of field measures has been conducted over and inside the forest canopy, using a vertical array of velocity sensors which includes a propeller anemometer, and x-hot wire and hot film anemometers.

A Preliminary Field Study of Turbulent Flow Over and Inside a Forest Edge

A Preliminary Field Study of Turbulent Flow Over and Inside a Forest Edge PDF Author: J. D. Lin
Publisher:
ISBN:
Category :
Languages : en
Pages : 116

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Book Description
This study focused on field measurements to determine the spatial variability of the turbulence characteristics under various atmospheric and forest canopy conditions. A high-speed multi-channel data acquisition system was configured and tested. Fixed and movable observation towers have been set up in the University experimental forest in Coventry, Conn. Two wind velocity sensors, being tested and evaluated in the laboratory for their capability to measure the three-dimensional flow with high turbulence intensity that generally characterizes the flow regime in a forest canopy; are a dual triple-split hot-film probe and a tri-diagonal hot-film probe with a wind octant electronic sensor (WOES). The response of WOES tested in the low-speed wind nozzle appears to be promising and its compatibility with the tri-diagonal hot-film probe is being evaluated. A number of field measures has been conducted over and inside the forest canopy, using a vertical array of velocity sensors which includes a propeller anemometer, and x-hot wire and hot film anemometers.

Scientific and Technical Aerospace Reports

Scientific and Technical Aerospace Reports PDF Author:
Publisher:
ISBN:
Category : Aeronautics
Languages : en
Pages : 704

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Field Study of Wind Through and Over a Forest Edge

Field Study of Wind Through and Over a Forest Edge PDF Author: D. R. Miller
Publisher:
ISBN:
Category :
Languages : en
Pages : 38

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Book Description
Three-dimensional miniature wind sensors that are stationary and have a high frequency response were developed and used to measure the wind structure inside and outside a forest edge. Extensive data sets were taken at different distances from the edge with the sensors arranged vertically through the canopy on movable towers both inside and outside the edge. Horizontally spaced sensors showed the flow inside the forest was correlated spatially at spacing less than 4 m. More persistent autocorrelations at higher wind speeds demonstrated that larger eddies penetrated the canopy at higher wind speeds. Measurements above the canopy demonstrated a decay of Reynolds stress with decreasing height in the roughness sublayer. Velocity spectra demonstrated that mechanical turbulence is generated by the canopy at frequencies of about 1 hz. Comparisons of in-forest profiles with the wind blowing into and out of the forest showed the effects of the edge on the turbulent intensities, streamwise and cross stream Reynolds stresses. The flow through the edge intensified the turbulences below and above the forest canopy. Conditional sampling analyses demonstrated the sweeping and ejection mechanism of large scale momentum transfer is modified by the edge. Measurements outside the edge show the evolution of intermittent stagnation eddies against the edge.

Government Reports Announcements & Index

Government Reports Announcements & Index PDF Author:
Publisher:
ISBN:
Category : Science
Languages : en
Pages : 1048

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Book Description


Wildland Fire Dynamics

Wildland Fire Dynamics PDF Author: Kevin Speer
Publisher: Cambridge University Press
ISBN: 1108580246
Category : Science
Languages : en
Pages : 263

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Book Description
Wildland fires are among the most complicated environmental phenomena to model. Fire behavior models are commonly used to predict the direction and rate of spread of wildland fires based on fire history, fuel, and environmental conditions; however, more sophisticated computational fluid dynamic models are now being developed. This quantitative analysis of fire as a fluid dynamic phenomenon embedded in a highly turbulent flow is beginning to reveal the combined interactions of the vegetative structure, combustion-driven convective effects, and atmospheric boundary layer processes. This book provides an overview of the developments in modeling wildland fire dynamics and the key dynamical processes involved. Mathematical and dynamical principles are presented, and the complex phenomena that arise in wildland fire are discussed. Providing a state-of-the-art survey, it is a useful reference for scientists, researchers, and graduate students interested in wildland fire behavior from a broad range of fields.

Government Reports Annual Index

Government Reports Annual Index PDF Author:
Publisher:
ISBN:
Category : Government reports announcements & index
Languages : en
Pages : 1672

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Book Description


Eddy Covariance

Eddy Covariance PDF Author: Marc Aubinet
Publisher: Springer Science & Business Media
ISBN: 9400723512
Category : Science
Languages : en
Pages : 451

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Book Description
This highly practical handbook is an exhaustive treatment of eddy covariance measurement that will be of keen interest to scientists who are not necessarily specialists in micrometeorology. The chapters cover measuring fluxes using eddy covariance technique, from the tower installation and system dimensioning to data collection, correction and analysis. With a state-of-the-art perspective, the authors examine the latest techniques and address the most up-to-date methods for data processing and quality control. The chapters provide answers to data treatment problems including data filtering, footprint analysis, data gap filling, uncertainty evaluation, and flux separation, among others. The authors cover the application of measurement techniques in different ecosystems such as forest, crops, grassland, wetland, lakes and rivers, and urban areas, highlighting peculiarities, specific practices and methods to be considered. The book also covers what to do when you have all your data, summarizing the objectives of a database as well as using case studies of the CarboEurope and FLUXNET databases to demonstrate the way they should be maintained and managed. Policies for data use, exchange and publication are also discussed and proposed. This one compendium is a valuable source of information on eddy covariance measurement that allows readers to make rational and relevant choices in positioning, dimensioning, installing and maintaining an eddy covariance site; collecting, treating, correcting and analyzing eddy covariance data; and scaling up eddy flux measurements to annual scale and evaluating their uncertainty.

Numerical Study of Scalar Advection in Canopies Using a Higher-order Closure Model

Numerical Study of Scalar Advection in Canopies Using a Higher-order Closure Model PDF Author: Young-San Park
Publisher:
ISBN:
Category :
Languages : en
Pages : 264

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Modelling Soil Erosion, Sediment Transport and Closely Related Hydrological Processes

Modelling Soil Erosion, Sediment Transport and Closely Related Hydrological Processes PDF Author: Wolfgang Summer
Publisher: IAHS Press
ISBN: 9781901502503
Category : Sediment transport
Languages : en
Pages : 468

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Flow Characteristics of Two Types of Springs in Southwestern Wisconsin

Flow Characteristics of Two Types of Springs in Southwestern Wisconsin PDF Author: Willie R. Curtis
Publisher:
ISBN:
Category : Hydrodynamics
Languages : en
Pages : 238

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Book Description