High-resolution numerical modeling of wave-supported gravity-driven mudflows
Ozdemir, Celalettin E.
Traykovski, Peter A.
MetadataShow full item record
Wave-supported gravity-driven mudflow has been identified as a major offshore fine sediment transport mechanism of terrestrial sediment into the coastal ocean. This transport process essentially occurs within the wave boundary layer. In this study, wave-supported gravity-driven mudflow is investigated via a wave-phase-resolving high-resolution numerical model for fluid mud transport. The model results are verified with field observation of sediment concentration and near-bed flow velocities at Po prodelta. The characteristics of wave-supported gravity-driven mudflows are diagnosed by varying the bed erodibility, floc properties (fractal dimension), and rheological stresses in the numerical simulations. Model results for moderate concentration suggest that using an appropriately specified fractal dimension, the dynamics of wave-supported gravity-driven mudflow can be predicted without explicitly incorporating rheological stress. However, incorporating rheological stress makes the results less sensitive to prescribed fractal dimension. For high-concentration conditions, it is necessary to incorporate rheological stress in order to match observed intensity of downslope gravity-driven current. Model results are further analyzed to evaluate and calibrate simple parameterizations. Analysis suggests that when neglecting rheological stress, the drag coefficient decreases with increasing wave intensity and seems to follow a power law. However, when rheological stress is incorporated, the resulting drag coefficient is more or less constant (around 0.0013) for different wave intensities. Model results further suggest the bulk Richardson number has a magnitude smaller than 0.25 and is essentially determined by the amount of available soft mud (i.e., the erodibility), suggesting a supply limited condition for unconsolidated mud.
Author Posting. © American Geophysical Union, 2009. 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 114 (2009): C05014, doi:10.1029/2008JC005006.
Showing items related by title, author, creator and subject.
Dean, Jerome P.; McCullough, C. B. (Woods Hole Oceanographic Institution, 1972-07)This report presents free air gravity values and computed free air anomalies obtained on an equatorial traverse from 09°00'E. to 37°56'W. It is the second of a series of reports presenting the gravity data to be used in ...
Hogg, Nelson G. (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1971-01)Observations of the ocean in the vicinity of Bermuda on two different occasions show systematic distortions of the isotherms close to the island and an area of intensive mixing on the northern coast. Two mechanisms are ...
Luther, Douglas S. (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1980-02)The existence of resonant, baroclinic, equatorially-trapped inertia-gravity waves (discovered by Wunsch and Gill (1976)) is confirmed in the mid-Pacific by spectral analysis of long sea level records. The energy of the ...