Berkeley Fluids Seminar

University of California, Berkeley

Bring your lunch and enjoy learning about fluids!

November 12, 2014

Exceptionally held in Hearst Field Annex B5

Nikola Marjanovic (Civil & Environmental Eng., UC Berkeley)

High-resolution atmospheric simulations and parameterizations for wind energy applications

Wind power forecasting, turbine micrositing, and turbine design require high-resolution simulations of atmospheric flow. Two case studies at two West Coast North American wind farms, one with simple and one with complex terrain, are explored using the Weather Research and Forecasting (WRF) model, a mesoscale atmospheric model, during both synoptically and locally forced conditions. The performance of the model with different grid nesting configurations, turbulence closures, and grid resolutions is investigated by comparison to observation data. For the simple terrain site, no significant improvement in the simulation results is found with higher resolution, however, there is significant improvement for the complex terrain site, but only during locally driven events. Upwind turbines are known to decrease wind speed and thus power output on downwind turbines, while at the same time increasing harmful turbulence intensity at the downstream turbine blades. A generalized actuator disk model (GAD) and a generalized actuator line model (GAL) are implemented into WRF. The parameterizations are designed for turbulence-resolving simulations, and are used within downscaled large-eddy simulations (LES) forced with mesoscale simulations and WRF’s grid nesting capability. The GAD distributes the thrust and torque created by a wind turbine blade on the atmosphere over a disk representing the rotor swept area, while the GAL tracks the location of the individual turbine blades and applies thrust and tangential forces at the temporal location of each blade, and in theory increasing the fidelity of the parameterization. The implementations are designed to permit simulation of turbine wake effects and turbine/airflow interactions within a realistic atmospheric boundary layer flow field.

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