Reynolds number trends from DNS of the turbulent Ekman layer

Direct numerical simulation of the neutrally stratified pressure-driven turbulent Ekman layer over a smooth flat surface has been performed at Reynolds number Re=2000 (based on geostrophic wind speed G, kinematic viscosity \nu and viscous boundary-layer depth D=\sqrt(2\nu/f), where f is the Coriolis parameter). The fully spectral Fourier/Jacobi MPI-based code has been run with a 1024\times1024\times200 grid on 104 processors of the UK HPCx IBM p690+ cluster, requiring approximately 100,000 CPU-node-hours to reach steady state and produce an adequate statistical sample. Results are used to quantify Reynolds number trends by comparing to earlier Re=400, 500 and 1000 DNS data. We are particularly interested in assessing the Spalart (1989) finite-Reynolds-number modification to the Csanady (1967) similarity theory for three-dimensional boundary layers, and implications for predicting the magnitude and direction of the surface shear stress at arbitrary Reynolds number