On the Relationship between Flow over 2d and 3d Forested Hills

In recent years, theories describing turbulent flow over forested two-dimensional ridges have emerged and are proving extremely useful in describing the coupling between the pressure drag imposed by the vegetation and the pressure drag associated with flow over two-dimensional terrain. While studies have been conducted of turbulent flow over three-dimensional terrain, the community has very little knowledge to date regarding a forest's impact on turbulent flow over three-dimensional hills. In this talk results from turbulence-resolving simulations of flow over a forested ridge and over two forested hills of similar character will be discussed to illuminate the key differences and their controlling processes.