Performance of the Cell Perturbation Method over Complex Terrain

Recent studies have demonstrated the challenge of generating turbulence in large-eddy simulations forced with smooth mesoscale forcing in a grid nesting framework. Very large fetches are needed for the flow to transition to resolved turbulence, which increases the computational demand of these simulations. To overcome this issue, a cell perturbation method has been developed and tested on mostly flat or idealized terrain with promising results. Additional work is needed to evaluate the performance of the cell perturbation approach in the presence of steep terrain features. In this work, we use the Weather Research and Forecasting model to simulate flow conditions at the site of the 2017 Perdigao field campaign in Portugal. Spectral analysis of the flow field is used to study the development of turbulence within the LES domain. The development of turbulence is compared to a standard model setup and to measurements obtained from soundings, meteorological towers, and Lidar.