| Abstrakt: |
Large-eddy simulation (LES) resolves large-scale turbulence directly and parametrizes small-scale turbulence. Resolving the micro-scale turbulence, e.g., in the wind turbine wakes, requires both a sufficiently small grid spacing and a domain large enough to develop the turbulent flow. Refining the grid locally via a nesting interface effectively decreases the required computational time compared to the global grid refinement. However, interpolating the flow between the nested grid boundaries introduces another source of uncertainty. Previous studies reviewed the nesting effects for a buoyancy-driven flow and observed a secondary circulation in the two-way nested area. Using nesting interface with a shear-driven flow in the wind field simulation, therefore, requires additional verification. We use PALM model system to simulate the boundary layer in a cascading selfnested domain under neutral, convective, and stable conditions, and verify the results based on the wind speed measurements taken at the FINO1 platform in the North Sea. We show that the feedback between the parent and child domain in a two-way nested simulation of a non-neutral boundary layer alters the circulation in the refined domain, despite the spectral characteristics following the reference measurements. Unlike the pure buoyancy-driven flow, the non-neutral shear-driven flow slows down in the two-way nested area and accelerates after exiting the child domain. We also briefly review the nesting effect on the velocity profiles and turbulence anisotropy. [ABSTRACT FROM AUTHOR] |
