Modification of turbulence characteristics in flow over hills

Abstract

Abstract A new model has been developed to investigate turbulence in flows over two‐dimensional hills: the von Mises transformation was applied in mean momentum equations, and turbulence equations (second‐order‐closure type) were solved in a coordinate system aligned with streamlines; the hill perturbation pressure was calculated by means of potential flow theory. the model predictions were compared with some experimental results from the Askervien Hill project with good agreement. It was found that apart from rapid distortion the curvature of streamlines has an important dynamical effect on turbulence. the curvature effect is shown to be particularly pronounced in the vicinity of the inner layer height on the hill top, where it attenuates turbulence. Overall, the salient features of the hill top turbulence profile were successfully explained by analysing the turbulence conservation equations in streamline coordinates.