Colloquium: 6 Feb 08, 4:10-5 pm in CR222

Note: This seminar is sponsored by the UW Departments of Math, Mechanical Engineering and Atmospheric Science.

Recent Large-eddy Simulations and Observations of Geophysical Boundary Layers

The advent of parallel computing has altered the landscape of turbulent simulations in the atmospheric and oceanic boundary layers.  Increased computer power using O(100-1000) processors permits large-eddy simulations (LESs) of turbulent flows to be carried out in more realistic outdoor environments, for example, flow over hills, boundary layers with surface water wave effects, and weakly stable nocturnal flows.  At the same time advances in our ability to obtain high quality spatial turbulence measurements in the atmospheric surface layer using arrays of sonic anemometers has provided new insights into subfilter scale models that appear in LES codes. In this talk I will give a brief overview from some recent LES of atmospheric boundary layers and ocean mixed layers that highlight the rich structure of boundary layer dynamics.  Also results from the ``Horizontal Array Turbulence Study" (HATS) and "Ocean Horizontal Array Turbulence Study" field campaigns will be presented.  These measurements are used to test subfilter scale parameterizations over a range of stratification and filter widths.  The implications for performing high Reynolds number rough-wall LES are then discussed.