Shelterbelts and windbreaks: Mathematical modeling and computer simulations of turbulent flows

Shelterbelts or windbreaks were used for centuries to reduce wind speed, to control heat and moisture transfer and pollutant diffusion, to improve cli mate and environment, and to increase crop yields; but only within the last few decades have systematic studies considered the aerodynamics and shelte r mechanisms of shelterbelts and windbreaks. This review examines recent mo deling and numerical simulation studies as well as the mechanisms that cont rol flow and turbulence around shelterbelts and windbreaks. We compare nume rical simulations with experimental data and explain the relationships betw een sheltering effects and the structure of shelterbelts and windbreaks. We discuss how and why the desired effects are achieved by using numerical an alysis. This chapter begins with the derivation of a general equation set f or porous shelterbelts and windbreaks; the numerical model and simulation p rocedure are developed; unseparated and separated flows are predicted and c haracterized; the momentum budget and shelter mechanisms are analyzed; the effects of wind direction, density, width, and three dimensionality of shel terbelt structure on flow and turbulence are systematically described. Rece nt modeling and simulation of heat flux and evapotranspiration are also sum marized. Finally, we discuss the use of highperformance distributed and par allel computing as well as clusters of networked workstations to enhance pe rformance of the model applied to simulations of shelterbelts and windbreak s.