Turbulence characteristics in wind-turbine wakes

An analysis of the evolution of turbulence characteristics in wind-turbine wakes has been carried out. Based on experimental results and on numerical results obtained with a CFD code, complemented with some theoretical considerations, simple analytical expressions are proposed for the estimation of the turbulent kinetic energy, k, and its dissipation rate, epsilon. To obtain the turbulence spectra in the wake a classical law used for atmospheric turbulence is assumed, in which characteristic values of turbulence velocity and turbulence length are calculated by algebraic combinations of k and epsilon, so that when the effect of the wake is negligible the spectrum of the unperturbed basic flow is recovered.