On the dynamics of turbulence near a free surface Articles uri icon

publication date

  • June 2017

start page

  • 248

end page

  • 265


  • 821

International Standard Serial Number (ISSN)

  • 0022-1120

Electronic International Standard Serial Number (EISSN)

  • 1469-7645


  • We report on direct numerical simulations to examine the spectral behaviour of turbulence close to and at a flat, stress-free surface. We find, consistent with field measurements near such a free surface, that an inertial-range type of behaviour is obtained for the horizontal components of the velocity at and near the stress-free surface, at horizontal wavelengths for which the vertical velocity is much smaller than the horizontal components. At approximately an integral length scale from the stress-free surface, the flow has adjusted back to more classical isotropic turbulence. The behaviour of the turbulence near the stress-free surface is similar to that observed recently for strongly stratified flows, and we argue that the causes of that behaviour are the same in both flows: the suppression of the large-scale vertical velocity and the allowance of strong vertical shearing of the horizontal velocity leading to a downscale transfer of energy and to the development of the -5/3 spectra for the horizontal velocities.


  • air/sea interactions; stratified turbulence; turbulence simulation; high-reynolds-number; water gas transfer; stratified turbulence; coherent structures; boundary-layers; channel flow; energy; simulation; transport; spectra