Spatially Evolving Turbulent Boundary-Layer Flow over a Wall-Mounted Cube

Turbulent flow over a wall-mounted cube presents an important canonical problem with applications in circuit design, urban building design, or aerodynamics. Flow over a cube placed in a fully developed turbulent channel flow has long been the preferred problem of investigation for researchers. However, a more relevant practical scenario is flow over a cube placed in a spatially evolving turbulent boundary layer (SETBL). In this work, wall-resolved largeeddy simulations of flow over a wall-mounted cube placed in an SETBL on a flat plate are performed at a Reynolds number of 19,600 based on the mean velocity and the inlet boundary-layer thickness. The incompressible Navier-Stokes equations are solved using a second-order finite-volume approach with a dynamic k-equation eddy-viscosity model. At this Reynolds number, the key nondimensional parameter governing this problem is the ratio of cube height to boundary-layer thickness, h/delta(o). This paper investigates the dependence of the turbulence wake characteristics on h/delta(o). Specifically, this paper analyzes the vortical structures and the separation and reattachment lengths. It is further examined how the turbulent kinetic energy budget varies with h/delta(o). It is found that the size of the horseshoe vortex roughly scales with the size of the cube, and that the decay of turbulent kinetic energy per unit area over streamwise distance in the near wake exhibits a power-law behavior.

Automated summary

This study investigates turbulent flow over a wall-mounted cube in a spatially evolving turbulent boundary layer using wall-resolved large eddy simulations. The research focuses on the dependence of turbulence wake characteristics on the ratio of cube height to boundary-layer thickness, and analyzes vortical structures, separation and reattachment lengths, as well as turbulent kinetic energy budget variations.