Abstract
Large eddy simulation (LES) of an infinitely long wind farm in a fully developed flow is carried out based on solution of the incompressible Navier-Stokes equations. The wind turbines are modeled as equivalent rotating actuator disks by applying aerodynamic loads on the flow field using tabulated aerodynamic lift and drag coefficients to save computational time. As a substitute to standard wall modeling LES, a ''prescribed mean shear" profile (hereafter called PMS) approach has been implemented and analysed for generating the desired turbulent shear flow. It is applied on Neutral, Stable and Convective atmospheric boundary layers in presence of the -actuator disc represented- wind turbines and qualitatively meaningful results of mean and fluctuating velocity field is obtained. The effect of four different sub-grid scale (SGS) models on the flow structure is investigated and it is seen that subgrid scale modeling (in particular, the Mix-O and Smagorinsky models) improves the accuracy of the simulations. An optimal grid resolution is also proposed for this kind of simulation.
Highlights
Direct simulation of wind turbines in the atmospheric boundary layer is impossible, at least for the near future, because of the need to resolve both the smallest and the large flow structures, requiring a total combination of grid cells and time steps of ∼ Re3 with the Reynolds number, Re, being in the order of 109
The main aim of this paper was to demonstrate the capability of Large eddy simulation (LES) simulations of an infinite wind turbine boundary layer with the PMS method, that is, exerting body forces to maintain a desired velocity profile and to show that these body forces are generally so smaller than the buoyancy effects and turbine body forces that allow for the turbulent wake structures to develop naturally
The results show that the PMS method gives reasonable estimates of the flow structures at different atmospheric boundary layer regimes, i.e. higher mixing and lower velocity deficit in the CBL case compared to the other cases
Summary
This content has been downloaded from IOPscience. Please scroll down to see the full text. 2014 J. Large Eddy Simulation of Wind Turbine Wakes in Prescribed Neutral and Non-Neutral Atmospheric
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