Author: Joseph H. Shinn
Publisher:
ISBN:
Category : Atmospheric circulation
Languages : en
Pages : 218
Book Description
New semi-empirical models are obtained of the mean momentum transport processes in and above forests for two contrasting micrometeorological problems: (1) the equilibrium air flow in forests far upwind of any inhomogeneity in the fetch, and (2) the nonequilibrium air flow in the transition region of the surface layer flow disturbed by the entrance into a forest. The study is confined to neutral stability conditions. Experimental data are from studies in eight forests and a wind tunnel simulation. The equilibrium mean velocity profiles in forest canopies are shown to be two-dimensional. A lateral component of flow increases downward from the top of the canopy. A semi-empirical model of mean velocity components is derived and verified for the upper 90% of the forest canopy depth. In the nonequilibrium flow in the transition region downwind of a forest wall: (a) The logarithmic velocity profile is found to be an empirical approximation for the lower part of the boundary layer, assuming that only the friction velocity varies with downstream distance. An empirical relation for the horizontal variation of the friction velocity is obtained. (b) The mean velocity profiles in a mixing zone located at midcanopy level are shown to have a low-level velocity maximum and horizontal similarity. (Author).
Steady-state Two-dimensional Air Flow in Forests and the Disturbance of Surface Layer Flow by a Forest Wall
Author: Joseph H. Shinn
Publisher:
ISBN:
Category : Atmospheric circulation
Languages : en
Pages : 218
Book Description
New semi-empirical models are obtained of the mean momentum transport processes in and above forests for two contrasting micrometeorological problems: (1) the equilibrium air flow in forests far upwind of any inhomogeneity in the fetch, and (2) the nonequilibrium air flow in the transition region of the surface layer flow disturbed by the entrance into a forest. The study is confined to neutral stability conditions. Experimental data are from studies in eight forests and a wind tunnel simulation. The equilibrium mean velocity profiles in forest canopies are shown to be two-dimensional. A lateral component of flow increases downward from the top of the canopy. A semi-empirical model of mean velocity components is derived and verified for the upper 90% of the forest canopy depth. In the nonequilibrium flow in the transition region downwind of a forest wall: (a) The logarithmic velocity profile is found to be an empirical approximation for the lower part of the boundary layer, assuming that only the friction velocity varies with downstream distance. An empirical relation for the horizontal variation of the friction velocity is obtained. (b) The mean velocity profiles in a mixing zone located at midcanopy level are shown to have a low-level velocity maximum and horizontal similarity. (Author).
Publisher:
ISBN:
Category : Atmospheric circulation
Languages : en
Pages : 218
Book Description
New semi-empirical models are obtained of the mean momentum transport processes in and above forests for two contrasting micrometeorological problems: (1) the equilibrium air flow in forests far upwind of any inhomogeneity in the fetch, and (2) the nonequilibrium air flow in the transition region of the surface layer flow disturbed by the entrance into a forest. The study is confined to neutral stability conditions. Experimental data are from studies in eight forests and a wind tunnel simulation. The equilibrium mean velocity profiles in forest canopies are shown to be two-dimensional. A lateral component of flow increases downward from the top of the canopy. A semi-empirical model of mean velocity components is derived and verified for the upper 90% of the forest canopy depth. In the nonequilibrium flow in the transition region downwind of a forest wall: (a) The logarithmic velocity profile is found to be an empirical approximation for the lower part of the boundary layer, assuming that only the friction velocity varies with downstream distance. An empirical relation for the horizontal variation of the friction velocity is obtained. (b) The mean velocity profiles in a mixing zone located at midcanopy level are shown to have a low-level velocity maximum and horizontal similarity. (Author).
Steady-state 2-dimensional Air Flow in Forests and Disturbance of Surface Level Flow by Forest Wall
Author: Joseph H. Shinn
Publisher:
ISBN:
Category : Forest canopies
Languages : en
Pages : 86
Book Description
Publisher:
ISBN:
Category : Forest canopies
Languages : en
Pages : 86
Book Description
An Annotated Bibliography of Wind Velocity Literature Relating to Forest Fire Behavior Studies
Author: Robert G. Baughman
Publisher:
ISBN:
Category : Forest fires
Languages : en
Pages : 32
Book Description
Publisher:
ISBN:
Category : Forest fires
Languages : en
Pages : 32
Book Description
Harvesting and Utilization Opportunities for Forest Residues in the Northern Rocky Mountains
Author:
Publisher:
ISBN:
Category : Logging
Languages : en
Pages : 804
Book Description
Publisher:
ISBN:
Category : Logging
Languages : en
Pages : 804
Book Description
Wastewater Aerosols and Disease
Author: H. Pahren
Publisher:
ISBN:
Category : Aerosols
Languages : en
Pages : 388
Book Description
Publisher:
ISBN:
Category : Aerosols
Languages : en
Pages : 388
Book Description
Application of the Ideal Canopy Flow Concept to Natural and Artificial Roughness Elements
Author: R. M. Cionco
Publisher:
ISBN:
Category : Air flow
Languages : en
Pages : 206
Book Description
Effort has been expended in modeling air flow within and above simple roughness elements for neutral steady-state conditions. Application of the ideal canopy flow concept suggested by Cionco, Ohmstede and Appleby is now extended to various natural and artificial canopies of simple or complex structure. Properties and characteristics considered were: Shape of the unit canopy wind profile, intensity of turbulence magnitudes, an index of canopy flow, and the effects of density and flexibility variations upon the flow. The profile shape is characteristic and best described by an exponential relationship within simple-structured elements. In complex structures, the profiles exhibited low-level maximums and no-gradient layers. Above the vegetation, the logarithmic wind relation was valid for each canopy type. Intensity of turbulence was relatively uniform with height for simple canopies and significantly non-uniform with height in complex structures, with large leaf area maximums and very low wind speeds. The ideal canopy flow concept can potentially serve many disciplines and efforts besides micrometeorology and diffusion research. If to serve no other purpose, it can be used to establish the initial formulation of a boundary condition or minor portion of a larger problem. The mathematical simplicity of the concept may be its most important quality when it is to be used as part of a larger system of equations.
Publisher:
ISBN:
Category : Air flow
Languages : en
Pages : 206
Book Description
Effort has been expended in modeling air flow within and above simple roughness elements for neutral steady-state conditions. Application of the ideal canopy flow concept suggested by Cionco, Ohmstede and Appleby is now extended to various natural and artificial canopies of simple or complex structure. Properties and characteristics considered were: Shape of the unit canopy wind profile, intensity of turbulence magnitudes, an index of canopy flow, and the effects of density and flexibility variations upon the flow. The profile shape is characteristic and best described by an exponential relationship within simple-structured elements. In complex structures, the profiles exhibited low-level maximums and no-gradient layers. Above the vegetation, the logarithmic wind relation was valid for each canopy type. Intensity of turbulence was relatively uniform with height for simple canopies and significantly non-uniform with height in complex structures, with large leaf area maximums and very low wind speeds. The ideal canopy flow concept can potentially serve many disciplines and efforts besides micrometeorology and diffusion research. If to serve no other purpose, it can be used to establish the initial formulation of a boundary condition or minor portion of a larger problem. The mathematical simplicity of the concept may be its most important quality when it is to be used as part of a larger system of equations.
General Technical Report INT
Author:
Publisher:
ISBN:
Category : Forests and forestry
Languages : en
Pages : 476
Book Description
Publisher:
ISBN:
Category : Forests and forestry
Languages : en
Pages : 476
Book Description
Estimating Production Rates and Operating Costs of Timber Harvesting Equipment in the Northern Rockies
Author: Charles W. George
Publisher:
ISBN:
Category : Aerial spraying and dusting in forestry
Languages : en
Pages : 332
Book Description
Publisher:
ISBN:
Category : Aerial spraying and dusting in forestry
Languages : en
Pages : 332
Book Description
Book catalog of the Library and Information Services Division
Author: Environmental Science Information Center. Library and Information Services Division
Publisher:
ISBN:
Category :
Languages : en
Pages : 444
Book Description
Publisher:
ISBN:
Category :
Languages : en
Pages : 444
Book Description
Book Catalog of the Library and Information Services Division: Subject index
Author: Environmental Science Information Center. Library and Information Services Division
Publisher:
ISBN:
Category : Book catalogs
Languages : en
Pages : 444
Book Description
Publisher:
ISBN:
Category : Book catalogs
Languages : en
Pages : 444
Book Description