Flow structures in the turbulent wake of a cross-flow wind turbine

Abstract

This article presents a description of the spatio-temporal flow structures found behind a cross-flow wind turbine under turbulent flow conditions. Higher order dynamic mode decomposition (HODMD) is applied to analyze both, the wake and the rotating area near the blades when simulated using a high order discontinuous Galerkin method with sliding meshes. The analysis of the flow velocities shows a marked asymmetry of the wake. This phenomenon is illustrated by the statistical analysis provided by a Reynolds decomposition and backed up through the dynamic mode analysis. Additionally, the results show that the flow is composed by a mode whose fundamental frequency is the frequency of rotation of the wind turbine and its harmonics. This fundamental frequency can be related to a traveling wave, moving in the streamwise direction of the flow.