Dynamics of Atmospheres and Oceans 38 (2005) 147–171 The effect of idealized water waves on the turbulence structure and kinetic energy budgets in the overlying airflow A. Rutgersson a,b,∗ , P.P. Sullivan a a National Center for Atmospheric Research, Boulder, CO 80307, USA b Department of Earth Sciences, Meteorology, Uppsala University, Villav 16, 752 36 Uppsala, Sweden Received 14 May 2004; received in revised form 1 October 2004; accepted 1 November 2004 Available online 2 February 2005 Abstract The influence of an idealized moving wavy surface on the overlying airflow is investigated us- ing direct numerical simulations (DNS). In the present simulations, the bulk Reynolds number is Re = 8000 (Re = U 0 h/v; where U 0 is the forcing velocity of the flow, h the height of the domain and v the kinematic viscosity) and the phase speed of the imposed waves relative to the friction ve- locity, i.e., the wave age varies from very slow to fast waves. The wave signal is clearly present in the airflow up to at least 0.15λ (where λ is the wave length) and is present up to higher levels for faster waves. In the kinetic energy budgets, pressure transport is mainly of importance for slow waves. For fast waves, viscous transport and turbulent transport dominate near the surface. Kinetic energy budgets for the wave and turbulent perturbations show a non-negligible transport of turbulent kinetic energy directed from turbulence to the wave perturbation in the airflow. The wave-turbulent energy transport depends on the size, tilt, and phase of the wave-induced part of the turbulent Reynolds stresses. According to the DNS data, slow waves are more efficient in generating isotropic turbulence than fast waves. Despite the differences in wave-shape as well as in Reynolds number between the idealized direct numerical simulations and the atmosphere, there are intriguing similarities in the turbulence structure. ∗ Corresponding author. Tel.: +46 18 471 2523; fax: +46 18 551 124. E-mail address: anna.rutgersson@met.uu.se (A. Rutgersson). 0377-0265/$ – see front matter © 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.dynatmoce.2004.11.001