Author: Zhen-jia Li
Publisher:
ISBN:
Category : Air flow
Languages : en
Pages : 96

Get Book Here

Book Description

Author: Günter Groß
Publisher: Springer Science & Business Media
ISBN: 364275676X
Category : Science
Languages : en
Pages : 243

Get Book Here

Book Description
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.

Author: Timothy James Phaneuf
Publisher:
ISBN:
Category :
Languages : en
Pages :

Get Book Here

Book Description
The computational fluid dynamics program, FLUENT, was first tested to validate windtunnel measurements of a scaled 10 ha forest clearing in a two dimensional domain. A variety of domain and canopy configurations were examined along with processor settings. Validation of the CFD program produced excellent results for horizontal wind velocity. Conifer shaped tree elements for the forest stands performed well and similar to the more traditional way of representing forest canopies. Turbulent kinetic energy (TKE) values output by the program seem to over predict the values calculated by using wind tunnel statistics. Various sizes of forest clearings were simulated to determine the stress that would be experienced by a forest edge immediately downwind of a clearing. Shorter gaps (15 tree heights) seem to experience high values of TKE over the downwind forest, compared to the stand upwind of the clearing and lower stress values along the downwind forest edge. Large gaps (60 tree heights) saw higher stress values but TKE values no larger than those reported upwind of the clearing. From the stress values calculated from various input velocities and gap sizes, a new tool was produced which takes into account a sites endemic wind speed and canopy density to predict stress on forest edges downwind of clearings.

Author: Timothy James Phaneuf
Publisher:
ISBN:
Category : Clearcutting
Languages : en
Pages : 0

Get Book Here

Book Description
The computational fluid dynamics program, FLUENT, was first tested to validate windtunnel measurements of a scaled 10 ha forest clearing in a two dimensional domain. A variety of domain and canopy configurations were examined along with processor settings. Validation of the CFD program produced excellent results for horizontal wind velocity. Conifer shaped tree elements for the forest stands performed well and similar to the more traditional way of representing forest canopies. Turbulent kinetic energy (TKE) values output by the program seem to over predict the values calculated by using wind tunnel statistics. Various sizes of forest clearings were simulated to determine the stress that would be experienced by a forest edge immediately downwind of a clearing. Shorter gaps (15 tree heights) seem to experience high values of TKE over the downwind forest, compared to the stand upwind of the clearing; and lower stress values along the downwind forest edge. Large gaps (60 tree heights) saw higher stress values but TKE values no larger than those reported upwind of the clearing. From the stress values calculated from various input velocities and gap sizes, a new tool was produced which takes into account a sites endemic wind speed and canopy density to predict stress on forest edges downwind of clearings.

Author: Asmae El Bahlouli-Öztürk
Publisher:
ISBN:
Category :
Languages : en
Pages : 0

Get Book Here

Book Description
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.

Author: Roger Pielke
Publisher: Springer
ISBN: 1935704125
Category : Science
Languages : en
Pages : 166

Get Book Here

Book Description
This book provides an overview of several components of mesoscale modeling: boundary conditions, subgrid-scale parameterization, moisture processes, and radiation. Also included are mesoscale model comparisons using data from the U.S. Army's Project WIND (Winds in Non-uniform Domains).

Author:
Publisher:
ISBN:
Category : Forests and forestry
Languages : en
Pages : 476

Get Book Here

Book Description

Author:
Publisher:
ISBN:
Category : Mechanics, Applied
Languages : en
Pages : 1072

Get Book Here

Book Description

Author: Charles W. George
Publisher:
ISBN:
Category : Aerial spraying and dusting in forestry
Languages : en
Pages : 332

Get Book Here

Book Description

Author: Gordon Bonan
Publisher: Cambridge University Press
ISBN: 1108611397
Category : Science
Languages : en
Pages : 459

Get Book Here

Book Description
Climate models have evolved into Earth system models with representation of the physics, chemistry, and biology of terrestrial ecosystems. This companion book to Gordon Bonan's Ecological Climatology: Concepts and Applications, Third Edition, builds on the concepts introduced there, and provides the mathematical foundation upon which to develop and understand ecosystem models and their relevance for these Earth system models. The book bridges the disciplinary gap among land surface models developed by atmospheric scientists; biogeochemical models, dynamic global vegetation models, and ecosystem demography models developed by ecologists; and ecohydrology models developed by hydrologists. Review questions, supplemental code, and modeling projects are provided, to aid with understanding how the equations are used. The book is an invaluable guide to climate change and terrestrial ecosystem modeling for graduate students and researchers in climate change, climatology, ecology, hydrology, biogeochemistry, meteorology, environmental science, mathematical modeling, and environmental biophysics.