Direct Numerical Simulation of the Turbulent Ekman Layer: Instantaneous Flow Structures

A direct numerical simulation of the turbulent Ekman layer at a Reynolds number of 400 was performed. Two-point velocity and pressure correlations were plotted to identify and estimate the average sizes and locations of instantaneous flow structures characteristic of turbulence. It was found that these structures are characterized by elongated eddies near the surface, which broaden away from the wall. The correlations roughly align with the mean shear direction near the surface; moving away from the wall, they exhibit tilting and lifting of downstream segments. The u' two-point correlation, in particular, showed significant tilting in the outer regions of the flow demonstrating that this is a significant deviation from typical nonrotating boundary-layer behavior.