Large-eddy simulation of the tidal-cycle variations of an estuarine boundary layer
Geyer, W. Rockwell
MetadataShow full item record
The estuarine boundary layer affected by a horizontal density gradient exhibits temporal evolution over a tidal cycle, in a manner similar to the diurnal cycle of the ocean surface mixed layer. A large eddy simulation (LES) model is developed to investigate the physics controlling the growth of the boundary layer during the flood tide and restratification during the ebb tide. Turbulent kinetic energy, momentum and salt fluxes, bottom stress, and energy dissipation rates calculated from the LES model all show a strong flood-ebb asymmetry. Analysis of the turbulent kinetic energy (TKE) budget shows a primary balance between shear production and dissipation in the well-mixed boundary layer over the tidal cycle. However, TKE transport term is found to be important across the edge of the boundary layer during the flood tide so turbulent energy generated in the bottom boundary layer can be transferred to the stratified pycnocline region. Tidal straining leads to a small and weakly convective region inside the boundary layer during the flood tide but the strain-induced buoyancy flux does not make a significant contribution to the turbulence generation. Additional LES runs are conducted by switching off the baroclinic pressure gradient term in the momentum equation and the tidal straining term in the salinity equation to show that the baroclinic pressure gradient is the main mechanism responsible for generating the flood-ebb mixing asymmetry.
Author Posting. © American Geophysical Union, 2010. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research 115 (2010): C08003, doi:10.1029/2009JC005702.
Suggested CitationArticle: Li, Ming, Radhakrishnan, Senthilkumaran, Piomelli, Ugo, Geyer, W. Rockwell, "Large-eddy simulation of the tidal-cycle variations of an estuarine boundary layer", Journal of Geophysical Research 115 (2010): C08003, DOI:10.1029/2009JC005702, https://hdl.handle.net/1912/3886
Showing items related by title, author, creator and subject.
Discontinuous hindcast simulations of estuarine bathymetric change : a case study from Suisun Bay, California Ganju, Neil K.; Jaffe, Bruce E.; Schoellhamer, David H. (Elsevier B.V., 2011-04-15)Simulations of estuarine bathymetric change over decadal timescales require methods for idealization and reduction of forcing data and boundary conditions. Continuous simulations are hampered by computational and data ...
Ralston, David K.; Geyer, W. Rockwell; Traykovski, Peter A.; Nidzieko, Nicholas J. (2012-01-25)Tidal flats at a river mouth feature estuarine and fluvial processes that distinguish them from tidal flats without river discharge. We combine field observations and a numerical model to investigate hydrodynamics and ...
Ganju, Neil K.; Schoellhamer, David H.; Jaffe, Bruce E. (American Geophysical Union, 2009-12-02)Hindcasting decadal-timescale bathymetric change in estuaries is prone to error due to limited data for initial conditions, boundary forcing, and calibration; computational limitations further hinder efforts. We developed ...