Numerical Simulation Of Canopy Flows
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Numerical Simulation Of Canopy Flows
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Author : Günter Groß
language : en
Publisher: Springer Science & Business Media
Release Date : 2012-12-06
Numerical Simulation Of Canopy Flows written by Günter Groß and has been published by Springer Science & Business Media this book supported file pdf, txt, epub, kindle and other format this book has been release on 2012-12-06 with Science categories.
Starting with the description of meteorological variables in forest canopies and its parameter variations, a numerical three-dimentional model is developed. Its applicability is demonstrated, first, by wind sheltering effects of hedges and, second, by the effects of deforestation on local climate in complex terrain. Scientists in ecology, agricultural botany and meteorology, but also urban and regional lanners will profit from this study finding the most effective solution for their specific problems.
Numerical Simulation Of Turbulent Flow And Microclimate Within And Above Vegetation Canopy
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Author : Hao-Chi Cynthia Poon
language : en
Publisher:
Release Date : 2017-01-26
Numerical Simulation Of Turbulent Flow And Microclimate Within And Above Vegetation Canopy written by Hao-Chi Cynthia Poon and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2017-01-26 with categories.
Numerical Simulation Of Turbulent Flow And Microclimate Within And Above Vegetation Canopy
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Author : Hao-chi Poon (Cynthia)
language : en
Publisher:
Release Date : 2010
Numerical Simulation Of Turbulent Flow And Microclimate Within And Above Vegetation Canopy written by Hao-chi Poon (Cynthia) and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2010 with Turbulence categories.
Large Eddy Simulations Of Canopy Flows Over Complex Terrain
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Author : Yulong Ma
language : en
Publisher:
Release Date : 2019
Large Eddy Simulations Of Canopy Flows Over Complex Terrain written by Yulong Ma and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2019 with categories.
Forest canopies cover about 30% of the land surfaces some of which are hilly or mountainous. Both complex terrain and forest canopies influence mean flow and turbulence, playing a critical role in affecting momentum and scalar transfer. Although recent advances have been made in numerical simulations of canopy flows, few have been conducted over steep slope terrain and considered full sets of physical and physiological processes in sub-canopy layers, which greatly limits our understanding of canopy flows and scalar transfer. To address this limitation, we upgrade the Weather Research and Forecasting model with the large-eddy simulations module (WRF-LES) by incorporating the immersed-boundary method (IBM) to improve the simulations over steep slope terrain. In addition, an advanced multiple layer canopy module (MCANOPY) is developed based largely on the Community Land Model version 4.5 and coupled with WRF-LES to simulate sources and/or sinks of momentum, heat, water vapor, and CO2 across multiple canopy layers. Both IBM and MCANOPY are evaluated against field measurements, demonstrating good performances compared with observations. The updated modeling system (i.e., WRF-LES-IBM-MCANOPY) is then applied over a forest edge to investigate the effects of foliage distributions and scalar distributions on canopy flows and scalar transfer. The results show that foliage distributions have a significant impact on the flow dynamics and scalar transfer, mainly due to the sub-canopy jet. The scalar distributions affect the scalar field with the ground source being the most important. The modeling system also simulates flows over forested hills. Flow dynamics over a three-dimensional hill show a different feature to those over a two-dimensional hill, where much large turbulence structures are simulated in the lee of a three-dimensional hill. Simulations over different slope hills demonstrate significant impacts of slopes. The lee side turbulence is enhanced as the hill slope increases. A new flow feature is the nearly unvarying flow field within the canopy in the lee of a steep slope hill, subjected to the influence of foliage distributions. Our upgraded WRF-LES-IBM-MCANOPY system has demonstrated promising capacities in many applications such as wind-turbine siting, wildfire propagation prediction, and interpretation of eddy covariance data over complex landscapes.
Numerical Modeling Of Atmospheric Boundary Layer Flow Over Forest Canopy
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Author : Konstantin Gavrilov
language : en
Publisher:
Release Date : 2011
Numerical Modeling Of Atmospheric Boundary Layer Flow Over Forest Canopy written by Konstantin Gavrilov and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2011 with categories.
The work is dedicated to the investigation of the interaction between an Atmospheric Boundary Layer and a canopy (representing a forest cover). We have focused our attention to the complex problem of the generation and transformation of turbulent vortices over homogeneous, heterogeneous and sparse canopy. This problem has been studied using Large Eddy Simulation (LES) approach and High Performance Computing (HPC) technique.The numerical results reproduced correctly all the main characteristics of this flow, as reported in the literature: the formation of a first generation of coherent structures aligned transversally with the wind flow direction, the reorganization and the deformation of these vortex tubes into horse-shoe structures. The results obtained with the introduction of a discontinuity in the canopy (reproducing a clearing or a fuel break in a forest) are compared with the experimental data collected in a wind tunnel. In this case, the results confirmed the existence of a strong turbulence activity inside the canopy at a distance equal to 8 times the height of the canopy, referenced in the literature as the Enhance Gust Zone (EGZ) characterized by a local peak of the skewness factor. Then, the process of passive scalar transport from a forest canopy into a clear atmosphere is studied for two cases, i.e., when the concentration held by the forest canopy is either constant or variable. While this difference has little influence on the concentration patterns, results show that it has an important influence on the concentration magnitude as well as on the dynamics of the total concentration in the atmosphere.
Large Eddy Simulation Of Turbulent Flow Above And Within A Plant Canopy
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Author : Edward Garrett Patton
language : en
Publisher:
Release Date : 1997
Large Eddy Simulation Of Turbulent Flow Above And Within A Plant Canopy written by Edward Garrett Patton and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1997 with categories.
Flow And Transport Processes With Complex Obstructions
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Author : Yevgeny A. Gayev
language : en
Publisher: Springer Science & Business Media
Release Date : 2007-02-06
Flow And Transport Processes With Complex Obstructions written by Yevgeny A. Gayev and has been published by Springer Science & Business Media this book supported file pdf, txt, epub, kindle and other format this book has been release on 2007-02-06 with Science categories.
This is the first book that reviews problems in different fluid mechanics disciplines that led to the concept of canopy, or penetrable roughness. Despite their diversity, many flows may be theoretically united by means of introducing distributed sinks and/or sources of momentum and heat and mass. These and other flows in engineering and environmental situations over surfaces with many obstacles are reviewed in terms of general concepts of fluid mechanics.
Numerical Study Of Canopy Flows In Complex Terrain
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Author : Xiyan Xu
language : en
Publisher:
Release Date : 2014
Numerical Study Of Canopy Flows In Complex Terrain written by Xiyan Xu and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2014 with categories.
Canopy flow plays a substantial role in regulating atmosphere-biosphere exchanges of mass and energy. The worldwide FLUXNET has been developed to quantify the net ecosystem exchange of mass and energy through fluid dynamics in and above vegetation canopy using tower-based eddy covariance (EC) technique. However, EC measurements are subject to advection errors in complex terrain, particularly during nights when atmospheric stability is strong. Because EC measurements are one-dimensional (1D), three-dimensional (3D) air movement, CO2 transport, and temperature variation around the instrumented tower are unknown. We employ a Computational Fluid Dynamics (CFD) model to investigate the impact on CO2 transport of 2D and 3D characteristics of canopy flow resulting from interactions between large-scale synoptic flows and local topography, vegetation and thermal conditions.
A Structured Fluids Approach To Canopy Flow
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Author : Mark N. Silbert
language : en
Publisher:
Release Date : 1970
A Structured Fluids Approach To Canopy Flow written by Mark N. Silbert and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1970 with Fluid dynamics categories.
The 'classical' turbulence approach to the flow of air in a vegetative canopy is reviewed. Three separate 'classical' theories are described. A comparison is made between experimentally measured canopy flows and a velocity function derived from the theory of structured continua. The agreement between theory and observations is good, but not unexpected, due to seven degrees of freedom in the fitted velocity profile. Proposals for future study for a more rigorous test of the theory are discussed.
Numerical Modelling Of Atmospheric Flows Over Complex Sites With Special Regard To The Forest Canopy
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Author : Asmae El Bahlouli-Öztürk
language : en
Publisher:
Release Date : 2021
Numerical Modelling Of Atmospheric Flows Over Complex Sites With Special Regard To The Forest Canopy written by Asmae El Bahlouli-Öztürk and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2021 with categories.
The present thesis describes the work carried out using the OpenFOAM solver with a Reynolds-Averaged Navier Stokes (RANS) approach to investigate the wind flow at complex sites for wind-energy exploitation. Toward this objective, several physical effects such as buoyancy, forest canopies, Coriolis forces, stratification as well as humidity have been implemented in the model to improve wind-field predictions. First, the wind flow in an urban environment and, more precisely, a university campus is investigated. A stationary logarithmic profile for the wind velocity at the inlet is prescribed. Despite the assumption of a flat terrain, which is a drastic simplification of the real ground, the study shows how a simple canopy model improves the prediction of the flow at the site. The simulation is validated with long term measurements from a network of six stations. Secondly, results from a rural case in the Swabian Alb in Southern Germany, characterized by a forested escarpment, are presented. The model is adapted to atmospheric boundary layer (ABL) flows and a computational domain with a ground conforming to the site orography is built. To get more realistic boundary conditions and to avoid the assumption of logarithmic profiles, the solver is coupled with a numerical weather prediction (NWP) model. The coupling is performed using a one-way approach, i.e the coarse weather model provides input to the OpenFOAM solver through the lateral boundary conditions of the computational domain. Simulations with and without forest are compared. The results with a canopy model clearly show at the lower levels a flow deceleration and an increase in turbulence intensities by a factor of four, when compared to results without forest. The study reveals again the important impact of the forest on the wind-field, especially at turbine-relevant heights. Finally, the transient approach (unsteady RANS) is tested by using time-dependent boundary conditions. The accuracy of the coupling is evaluated by validating the simulation results against measurements from a tall meteorological tower as well as an unmanned aircraft system. Adopting a transient approach leads to an excellent agreement of the model. The thesis shows that an unsteady RANS based solver, which accounts for first-order relevant physics, can be valuable for a wind resource assessment at low computational cost compared to detached-eddy (DES) or large-eddy (LES) simulations.