Posters

Abstract

Determining simulation uncertainties is essential for accurately assessing wind energy yield. It improves the general uncertainty analysis of a project by not just guessing simulation uncertainties and thus makes the site assessment more reliable. The high number of potential sources of simulation uncertainty poses a significant challenge for uncertainty assessment in Computational Fluid Dynamics (CFD) simulations in this field. One source of uncertainty is the discretization error that results from the numerical solution of the underlying equations. In addition, uncertainties arise from the input data's uncertainty and the choice of model settings. And finally, the uncertainty is determined by site characteristics like roughness changes and orography. Despite the importance of quantitative findings on the magnitude of these uncertainty sources for site assessment using CFD in wind energy, they have not been sufficiently investigated. To address this gap, the project SUnDAY, funded by the German Federal Ministry for Economic Affairs and Energy (BMWi) and coordinated by Fraunhofer IWES in collaboration with GEO-NET Umweltconsulting GmbH and other industrial partners, aimed to estimate the expected model uncertainties prior to simulations for FITNAH-3D and other CFD models. This estimate should be based solely on previously known information, such as topographical data, enabling the selection of the best setup, such as domain size and resolution, for a simulation based on site conditions, acceptable level of uncertainty, and costs. The study analyzed several sites with different conditions and simulation setups, with at least two measurement positions each. Prediction errors for one position were calculated using the other position as a reference. For each pair, the ratio of physical site parameters, such as roughness length and complexity, was calculated as a measure of the site conditions. The simulated prediction errors were then correlated with these measures to find a suitable predictor for future investigations.