Locations with steep changes in the terrain elevation, as is typically the Greek country, are difficult cases for the “traditional” calculation tools for the estimation of the wind potential energy. Simulations without CFD (Computational Fluid Dynamics) technology may be of poor accuracy and therefore cause negative effects on the economic exploitation of the wind park and reduced efficiency.
SimTec performed CFD simulations for the wind flow over a geographical site in Greece, in order to assess its wind energy potential before the installation of a wind farm. The terrain shape was taken from GIS (Geographic Information System) data from the Hellenic Military Geographical Service, more specifically from 30×30 [m] data series. The solution area extends from the farm site from all sides, so that the software can correctly predict the development of the atmospheric boundary layer.
The air flow was calculated for all 16 wind directions (N, S, E, W, NW, NE, SW, SE, NNW, NNE, SSW, SSE, ENE, ESE, WNW, WSW) and for various wind velocity magnitudes, according to the statistical processing of available wind history data for the past few decades taken from nearby meteorological measuring stations. The wind velocity profile at the inlet of the domain was prescribed according to the standard power law for the turbulent atmospheric boundary layer as correlated with measurements at 10 [m] height.
The solution of all these cases resulted in mapping the wind energy potential at the wind turbine rotor height as a function of wind direction and velocity magnitude. Hence, it is possible to statistically estimate the economical potential of a wind farm installation, depending on the prevailing wind conditions in the over the year.
The CFD study included:
- Creation of the geometric model from GIS data (coordinates of 120000 points: geographical latitude, geographical altitude and terrain elevation) and creation of the computational mesh in pre-processor GAMBIT.
- Solution of the air flow inside a volume of 10×10 [km] area and 1 [km] height over the highest elevation of the greater area, whereas the site of interest has a surface of 227,000 square meters.
Typical results are the distribution of the wind velocity magnitude and direction at the height of the wind turbine rotors. In addition there is an option to include the turbines themselves into the analysis, so as to estimate the influence of their operation between them and on the total produced energy (wind turbine shadowing).