Our group is currently developing a Large-Eddy Simulation (LES) framework for the prediction of atmospheric boundary layer turbulence and its interactions with wind turbines and wind energy farms. This numerical modeling framework will provide objective, scientifically based criteria that can be used by wind energy project developers for the site-specific, optimal selection and placement (micro-siting) of wind turbines. Funding for this research is provided by Xcel Energy (Renewable Development Fund) and the University of Minnesota Initiative for Renewable Energy and the Environment.
Our current research efforts focus on developing and testing physically-based models needed to represent subgrid-scale turbulent fluxes/stresses (e.g., Stoll and Porté-Agel, 2006, 2008, 2009; Wan et al, 2007) and turbine forces in the context of LES. This is achieved via analysis of high-resolution turbulence data collected in the St. Anthony Falls Laboratory atmospheric boundary layer wind tunnel. In particular, hot-wire anemometry and particle-image velocimetry (PIV) are being used to characterize the flow around miniature wind turbines placed in the turbulent boundary layer over different surface roughness, topography and thermal stratification conditions (e.g., Chamorro and Porté-Agel, 2009).
In the near future, we plan to extend our data analysis and modeling framework to wind and turbulence data collected in a Minnesota wind farm. The field measurements will be collected in collaboration with our partners from WindLogics and Barr Engineering during the Fall of 2009.
Wind-tunnel studies for wind energy
Figure 1. Contour plots of the measured averaged velocity (top), turbulence intensity (middle), kinematic shear stress (bottom) in the wake of the wind turbine. Dots represent measurement locations.
Large-eddy simulation for wind energy
Figure 2. Simulation results obtained using LES with a Lagrangian scale-dependent dynamic model: averaged velocity (top), turbulence intensity (middle), kinematic shear stress (bottom).
Figure 3. Comparison between measured and simulated vertical profiles (at the middle and downwind distance x/d=5) of averaged velocity and turbulence intensity.
Publications
Chamorro, L. and F. Porté-Agel. A wind-tunnel investigation of wind-turbine wakes: Boundary-layer turbulence effects. Boundary-Layer Meteorol, 2009 (accepted for publication). available here
Stoll, R., and Porté-Agel F., Surface heterogeneity effects on regional-scale fluxes in stable boundary layers: surface temperature transitions, Journal of the Atmospheric Sciences , 2009. available here
Stoll, R., and Porté-Agel F., Large-eddy simulation of the stable atmospheric boundary layer using dynamic models with different averaging schemes, Boundary-Layer Meteorology, 126, 1-28, 2008. available here
Wan, F. , Porté-Agel F., and Stoll R., Evaluation of dynamic subgrid-scale models in large-eddy simulations of neutral turbulent flow over a two-dimensional sinusoidal hill, Atmospheric Environment, doi: 10.1016/j.atmosenv.2006.11.054, 2007. available here
Stoll R, Porté-Agel F, Dynamic subgrid models for momentum and scalar fluxes in large-eddy simulations of neutrally startified atmospheric boundary layers over heterogeneous terrain, Water Resources Research, 42, 1. w01409, doi: 10.1029/2005WR003989, 2006. available here
Conference Presentations
Porté-Agel, F., Y.-T. Wu and L. Chamorro. Modeling subgrid-scale fluxes and wind-turbine forces in large-eddy simulation. European Geosciences Union, Vienna, Austria, April 2009.
Wu, Y.-T. and F. Porté-Agel. Numerical modeling of wind turbine wakes using large eddy simulation. European Geosciences Union, Vienna, Austria, April 2009.
Chamorro, L. and F. Porté-Agel. Surface roughness and thermal stratification effects on the structure of wind turbine wakes. European Geosciences Union, Vienna, Austria, April 2009.
Wu, Y.-T. and F. Porté-Agel. LES of wind turbine wakes: Evaluation of turbine parameterizations and dynamic subgrid-scale models. Fall Meeting of American Geophysical Union, San Francisco, California, December 2008.
Chamorro, L. and F. Porté-Agel. A wind tunnel investigation of wind turbine wakes: Boundary-layer turbulence and surface roughness effects. Fall Meeting of American Geophysical Union, San Francisco, California, December 2008.
Chamorro, L., Y.-T. Wu, and F. Porté-Agel. Turbuence effects on wind turbines: A wind-tunnel study. 18th Symposium on Boundary Layers and Turbulence of the American Meteorological Society, Stockholm, Sweden, June 2008.
