Numerical evidence of turbulence generated by nonbreaking surface waves
Journal
Journal of Physical Oceanography
Journal Volume
45
Journal Issue
1
Pages
174-180
Date Issued
2015
Author(s)
Abstract
Numerical simulation of monochromatic surface waves propagating over a turbulent field is conducted to reveal the mechanism of turbulence production by nonbreaking waves. The numerical model solves the primitive equations subject to the fully nonlinear boundary conditions on the exact water surface. The result predicts growth rates of turbulent kinetic energy consistent with previous measurements and modeling. It also validates the observed horizontal anisotropy of the near-surface turbulence that the spanwise turbulent intensity exceeds the streamwise component. Such a flow structure is found to be attributed to the formation of streamwise vortices near the water surface, which also induces elongated surface streaks. The averaged spacing between the streaks and the depth of the vortical cells approximates that of Langmuir turbulence. The strength of the vortices arising from the wave-turbulence interaction, however, is one order of magnitude less than that of Langmuir cells, which arises from the interaction between the surface waves and the turbulent shear flow. In contrast to Langmuir turbulence, production from the Stokes shear does not dominate the energetics budget in wave-induced turbulence. The dominant production is the advection of turbulence by the velocity straining of waves. © 2015 American Meteorological Society.
Subjects
Atm/Ocean Structure/Phenomena; Laboratory/physical models; Marine boundary layer; Microscale processes/variability; Models and modeling; Nonhydrostatic models; Surface layer; Vortices
Other Subjects
Boundary layers; Budget control; Computational fluid dynamics; Kinetic energy; Kinetics; Nonlinear equations; Numerical models; Shear flow; Surface waves; Turbulence; Vortex flow; Water waves; Laboratory/physical models; Marine boundary layers; Microscale processes/variability; Nonhydrostatic model; Surface layers; Atmospheric thermodynamics; advection; atmospheric structure; boundary layer; computer simulation; flow modeling; kinetic energy; marine atmosphere; numerical model; shear flow; surface wave; turbulence; vorticity; wave generation; wave propagation
Type
journal article