Turbulent Speed
VTKE is defined as the square root of the Turbulent Kinetic Energy (TKE), expressed in meters per second (m/s). It represents the average magnitude of wind speed fluctuations in all three dimensions.
Relation to other turbulence fields
TKE is a measure of the kinetic energy per unit mass associated with eddies in turbulent flow. It is calculated using the variances of the wind velocity components in all three directions (u′, v′, w′).
VTKE is closely related to turbulence intensity, a dimensionless measure of turbulence strength. Turbulence intensity is typically defined as the ratio of the standard deviation of wind speed fluctuations to the mean wind speed.
Dependence on Mean Wind Speed
VTKE generally increases with mean wind speed, but the relationship is not always linear. The exact relationship can vary depending on atmospheric conditions and terrain.
Vertical Variation
VTKE and turbulence intensity typically vary with height above the ground. In the atmospheric boundary layer, turbulence intensity often decreases with height as the influence of surface roughness diminishes.
Applications
VTKE is used in various atmospheric and wind energy applications, including:
- Characterizing the turbulence environment for wind turbines: Helps in understanding the effects of turbulence on turbine performance and lifespan.
- Assessing the potential for atmospheric dispersion of pollutants: Provides insights into how pollutants disperse in turbulent wind conditions.
- Studying atmospheric boundary layer dynamics: Aids in understanding the behavior of the atmospheric boundary layer, including turbulence and wind shear.
Importance of VTKE
Understanding VTKE is crucial for various applications in wind engineering, atmospheric science, and renewable energy. It provides valuable information about the turbulent nature of the wind
- Airport: VTKE is central to airport air safety for planes during the landing and takeoff phases, where turbulence can significantly impact aircraft stability and control.