DNS of Spatially-Developing Three-Dimensional Turbulent Boundary Layers

Abstract

Many experimental, numerical and theoretical studies are available dealing with the physics of turbulent boundary layers (TBL) with a two-dimensional mean-flow profile, i.e., the velocity component in the spanwise direction is vanishing. Moreover, external pressure gradients (e.g., favorable, FPG) are usually introduced to be aligned with the mean flow. However, most relevant flows in nature and technical applications tend to occur on curved surfaces, and they usually include a certain crossflow component. Studies of 3D boundary layers can be found in, e.g., Refs. [3, 4]. In 3D boundary layers different factors may be responsible for the various changes in statistical quantities with respect to the unswept case. In particular, the three-dimensionality may be introduced via streamwise vorticity generated at the wall (e.g., via a impusively started moving wall leading to a transient, non-equilibrium state) or via pressure gradients not aligned with the free-stream velocity.