Analysis of Obstacle and Soil Roughness Effects on the Wind Speed Profile by Using the Finite Element Method

Wind velocity variations near the ground correspond to turbulence effects, which are associated to shear occurring in the boundary layer due to the ground surface roughness and the presence of some obstacles. Computational fluid dynamics is used in this work in order to model these effects. The objective is to estimate the profile of the wind speed for various ground conditions with the aim to estimate more accurately the extractable energy from wind kinetic energy. A three-dimensional model describing the atmospheric circulations that are induced by the presence of an obstacle having the form of a hill and soil roughness was developed. The hill profile was schematized by a spherical surface and surface roughness by a scaled parameter. Appropriate boundary layer conditions were applied. Precision of the model was examined as function of the location of the boundary fixing the truncated computational domain of air and also the mesh size used. The boundary condition at the ground surface was fixed by a wall law. The obtained results have shown that the wind speed decreases when the obstacle height roughness increases. In addition to the main effect due to the presence of a hill, surface details such as bushes can significantly degrade the wind potential.