SHELTERBELTS ANDWINDBREAKS:Mathematical Modeling and Computer Simulations of Turbulent Flows

Abstract

Shelterbelts or windbreaks have been used for centuries to reduce wind speed, to control heat and moisture transfer and pollutant diffusion, to improve climate and environment, and to increase crop yields; but only within the last few decades have systematic studies considered the aerodynamics and shelter mechanisms of shelterbelts and windbreaks. This is a review of recent modeling and numerical simulation studies as well as the mechanisms that control flow and turbulence around shelterbelts and windbreaks. We compare numerical simulations with experimental data and explain the relationships between sheltering effects and the structure of shelterbelts and windbreaks. We discuss how and why the desired effects are achieved by using numerical analysis. This chapter begins with the derivation of a general equation set for porous shelterbelts and windbreaks; the numerical model and simulation procedure are developed; unseparated and separated flows are predicted and characterized; the momentum budget and This article has been accepted for publication by Annual Reviews in a revised form. 23shelter mechanisms are analyzed; the effects of wind direction, density, width, and three dimensionality of shelterbelt structure on flow and turbulence are systematically described.Recent modeling and simulation of heat flux and évapotranspiration also are summarized.Finally, we discuss use of high-performance distributed and parallel computing as well as clusters of networked workstations to enhance performance of the model applied to simulations of shelterbelts and windbreaks.

Simulating the growth of tafoni

“…Inside the cavity the situation is more complex. Generally, flows are suppressed to a certain extent in regions sheltered from the wind, which fact is used in agriculture to reduce the evaporation rate of water (Wang et al, 2001). Therefore, we expect that airflows due to wind will be less inside than outside a cavity and a gradient in the vapour the density can develop (Prata and Sparrow, 1985).…”

“…Although it has been claimed that such fluctuations exist above rough surfaces (Rodriguez-Navarro et al, 1999), there is no evidence that this effect plays a role in large cavities like tafoni. Generally, behind a shelterbelt or in a depression the wind speed is reduced, which is widely used to protect crops from excessive evaporation (Wang et al, 2001). We have explicitly used this fact in our model.…”

Deposition of Aerially Applied Spray to a Stream within a Vegetative Barrier

“…When airborne spray encounters a vegetative barrier, it is expected that some of the material will be captured, but data confirming this are sparse. Ucar and Hall (1999) conducted recent literature reviews of spray capture by vegetative barriers, and Wang and Takle (1995, 1997) and Wang et al (2001) produced a detailed model of the airflow around vegetative barriers. Tuzet and Wilson (2007) largely confirmed the physical model proposed in the above work.…”

Modelling of diffusion boundary-layers in subtidal macroalgal canopies: The response to waves and currents

“…In addition the porosity of the canopy is important. Shelterbelt studies provide a useful comparison showing how velocities through a single band of trees can be reduced significantly (Wang et al, 2001) depending on the porosity.…”