A numerical simulation of boundary-layer flows near shelterbelts

We have developed a shelterbelt boundary-layer numerical model to study the patterns and dynamic processes relating to flow interaction with shelterbelts. The model simulates characteristics of all three zones of airflow passing over and through shelterbelts: the windward windspeed-reduction zone, the overspeeding zone above the shelterbelt, and the leeward windspeed-reduction zone. Locations of the maximum windspeed reduction and recirculation zone, as well as the leeward windspeed-recovery rate are well simulated by the model. Where comparisons with field measurements and wind-tunnel experiments were possible, the model demonstrated good performance for flows over and through shelters ranging from almost completely open to almost solid.The dynamic pressure resulting from the convergence and divergence of the flow field alters the perturbation pressure field. The disturbed pressure controls not only the formation of the separated flow but also the location of maximum windspeed reduction, streamline curvature, speed-up over the shelterbelt, and leeward windspeed recovery rate. The interaction of pressure with the flow produces complex flow patterns, the characteristics of which are determined, to a great extent, by shelterbelt structure.

[1]  W. D. Baines,et al.  An Investigation of Flow Through Screens , 1951, Journal of Fluids Engineering.

[2]  J. Caborn.  Shelterbelts and microclimate , 1957 .

[3]  Shi Chang,et al.  VELOCITY DISTRIBUTIONS IN THE SEPARATED FLOW BEHIND A WEDGE SHAPED MODEL HILL , 1966 .

[4]  A. Chorin.  Numerical solution of the Navier-Stokes equations , 1968 .

[5]  Stephen Whitaker,et al.  ADVANCES IN THEORY OF FLUID MOTION IN POROUS MEDIA , 1969 .

[6]  Alexandre J. Chorin,et al.  On the Convergence of Discrete Approximations to the Navier-Stokes Equations , 1969 .

[7]  I. Castro.  Wake characteristics of two-dimensional perforated plates normal to an air-stream , 1971, Journal of Fluid Mechanics.

[8]  L. J. Hagen,et al.  Turbulent Velocity Fluctuations and Vertical Flow as Affected by Windbreak Porosity , 1971 .

[9]  Erich J. Plate,et al.  The aerodynamics of shelter belts , 1971 .

[10]  P. Riekkinen,et al.  Studies on the pathogenesis of multiple sclerosis. 2',3'-Cyclic nucleotide 3-phosphohydrolase as marker of demyelination and correlation of findings with lysosomal changes. , 1972, Journal of the neurological sciences.

[11]  Stephen Whitaker,et al.  The transport equations for multi-phase systems , 1973 .

[12]  G. Mellor,et al.  A Hierarchy of Turbulence Closure Models for Planetary Boundary Layers. , 1974 .

[13]  P. S. Jackson,et al.  Wakes behind two-dimensional surface obstacles in turbulent boundary layers , 1974, Journal of Fluid Mechanics.

[14]  George L. Mellor,et al.  A Simulation of the Wangara Atmospheric Boundary Layer Data , 1975 .

[15]  R. Welch,et al.  Implicit Differencing of Predictive Equations of the Boundary Layer , 1976 .

[16]  N. Wilson,et al.  A Higher Order Closure Model for Canopy Flow , 1977 .

[17]  D. C. Stevenson,et al.  Wind protection by model fences in a simulated atmospheric boundary layer , 1977 .

[18]  L. J. Hagen,et al.  Simulation of Effect of Wind Barriers on Airflow , 1980 .

[19]  M. Perera,et al.  Shelter behind two-dimensional solid and porous fences , 1981 .

[20]  Stephen Whitaker,et al.  Introduction to fluid mechanics , 1981 .

[21]  M. Raupach,et al.  Averaging procedures for flow within vegetation canopies , 1982 .

[22]  Tetsuji Yamada,et al.  A numerical model study of turbulent airflow in and above a forest canopy , 1982 .

[23]  G. Mellor,et al.  Development of a turbulence closure model for geophysical fluid problems , 1982 .

[24]  E. F. Bradley,et al.  THE TURBULENT KINETIC ENERGY BUDGET BEHIND A POROUS BARRIER: AN ANALYSIS IN STREAMLINE CO-ORDINATES , 1983 .

[25]  E. F. Bradley,et al.  Development of velocity and shear stress distribution in the wake of a porous shelter fence , 1983 .

[26]  John D. Wilson,et al.  Numerical studies of flow through a windbreak , 1985 .

[27]  J. Finnigan,et al.  Turbulent Transport in Flexible Plant Canopies , 1985 .

[28]  T. Meyers,et al.  Testing of a higher-order closure model for modeling airflow within and above plant canopies , 1986 .

[29]  John D. Wilson,et al.  On the choice of a windbreak porosity profile , 1987 .

[30]  Gordon M. Heisler,et al.  2. Effects of windbreak structure on wind flow , 1988 .

[31]  John D. Wilson,et al.  A second-order closure model for flow through vegetation , 1988 .

[32]  K. G. McNaughton,et al.  1 – Effects of Windbreaks on Turbulent Transport and Microclimate , 1988 .

[33]  P. Taylor.  Turbulent Wakes in the Atmospheric Boundary Layer , 1988 .

[34]  Y. Mahrer,et al.  Modeling microclimate environments: A verification study , 1989 .

[35]  David R. Miller,et al.  Air flow over and through a forest edge: A steady-state numerical simulation , 1990 .

[36]  Y. Mahrer,et al.  Two-dimensional microclimate distribution within and above a crop canopy in an arid environment: Modeling and observational studies , 1991 .

[37]  David R. Miller,et al.  Air flow across an alpine forest clearing: A model and field measurements , 1991 .

[38]  Eugene S. Takle,et al.  Boundary-layer flow and turbulence near porous obstacles , 1995 .