Monday, 11 June 2018: 9:40 AM
Ballroom D (Renaissance Oklahoma City Convention Center Hotel)
The marine atmospheric and oceanic boundary layers are abundant
with small and large-scale fluid dynamical processes interconnected
in complex ways. Spray, bubbles, vortical structures, buoyant plumes,
internal waves, and Langmuir and submesoscale turbulence are some
of the known processes that couple to influence the important
vertical transport of momentum and scalars [1]. Furthermore, the air-water
boundary layers are separated by a randomly evolving multi-scale
wavy interface that breaks intermittently under high winds. Because
of advances in computational power, massively parallel turbulence
simulation technology is now capable of providing new insights into
the complex processes at work in the marine boundary layers.
Large-eddy and direct numerical simulations (LES and DNS) with 10^9
or more gridpoints using 10^4 or more computational cores are near
commonplace on the current generation of peta-scale machines. In
this talk, I will present highlights from recent LES configured to
isolate coupling across disparate scales in the marine boundary
layers. In particular, ocean boundary-layer dynamics driven by
surface winds and waves coupled to submesoscale density filaments.
These simulations illustrate boundary-layer induced frontogenesis
and emphasize the important role of small-scale turbulence in
frontogenetic arrest [2]. Next, I will consider turbulent airflow
over moving waves with a focus on the aerodynamics above steep
steady and unsteady wave trains and the impact on surface drag [3].
Lastly, I will briefly describe a newly developed fringe technique
that permits the coupling of the marine atmospheric boundary layer
with heterogeneous SST gradients. Although these LES are configured
as idealized process studies they provide hints at potential research
avenues for future field observations.
with small and large-scale fluid dynamical processes interconnected
in complex ways. Spray, bubbles, vortical structures, buoyant plumes,
internal waves, and Langmuir and submesoscale turbulence are some
of the known processes that couple to influence the important
vertical transport of momentum and scalars [1]. Furthermore, the air-water
boundary layers are separated by a randomly evolving multi-scale
wavy interface that breaks intermittently under high winds. Because
of advances in computational power, massively parallel turbulence
simulation technology is now capable of providing new insights into
the complex processes at work in the marine boundary layers.
Large-eddy and direct numerical simulations (LES and DNS) with 10^9
or more gridpoints using 10^4 or more computational cores are near
commonplace on the current generation of peta-scale machines. In
this talk, I will present highlights from recent LES configured to
isolate coupling across disparate scales in the marine boundary
layers. In particular, ocean boundary-layer dynamics driven by
surface winds and waves coupled to submesoscale density filaments.
These simulations illustrate boundary-layer induced frontogenesis
and emphasize the important role of small-scale turbulence in
frontogenetic arrest [2]. Next, I will consider turbulent airflow
over moving waves with a focus on the aerodynamics above steep
steady and unsteady wave trains and the impact on surface drag [3].
Lastly, I will briefly describe a newly developed fringe technique
that permits the coupling of the marine atmospheric boundary layer
with heterogeneous SST gradients. Although these LES are configured
as idealized process studies they provide hints at potential research
avenues for future field observations.
[1] Sullivan, P.P. & J. C. McWilliams, 2010:
Dynamics of winds and currents coupled to surface waves. Annual
Review of Fluid Mechanics, 42, 19-42.
[2] Sullivan, P. P. & J. C. McWilliams, 2018:
Frontogenesis and frontal arrest of a dense filament in the
oceanic surface boundary layer. Journal of Fluid Mechanics,
837, 341-380.
[3] Sullivan, P. P., M. L. Banner, R. P. Morisson & W. L. Peirson,
Turbulent flow over steep steady and unsteady waves under strong
wind forcing. Journal of Physical Oceanography, 48, 3-27.
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