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The AAPG/Datapages Combined Publications Database

CSPG Special Publications

Abstract


Shelf Sands and Sandstones — Memoir 11, 1986
Pages 339-339
Symposium Abstracts: Storm-Dominated Shelves

Experimental Evaluation of Generalized Suspended Sediment Transport Theory: Abstract

Guy Gelfenbaum1, J. Dungan Smith2

Abstract

Accurate, physically-based sediment transport and flow theories that are applicable under a wide range of conditions are important to marine geological problems, both modem and ancient. Interpretation of ancient environments and predictions for modern, difficult to measure processes, such as continental shelf storms or turbidity currents, rely heavily on generalized theories. To accommodate this need for a more generalized suspended sediment transport theory, higher-order effects, such as multicomponent sediment distribution, sediment-induced density stratification, and near-bottom flow field interaction have recently been added to existing theories. In order to evaluate the usefulness of these and other complicating additions under controlled conditions, the present generalized gravitational theory of Smith and McLean (1977) was tested against the laboratory flume experiments of Vanoni (1946), and Einstein and Chien (1955). Combining data from these experiments allows the theory to be tested against a wide range of sediment and flow parameters. Settling velocities range from 1.18 to 17.25 cm/s, nondimensional volume concentrations from 2.5 × 10-7 to 2.3 × 10-1, and shear velocities from 2.5 to 18 cm/s. Results of comparisons between the theory and experiments show that the theory works well under a wide range of sediment and flow conditions in predicting vertical-velocity and suspended-sediment profiles. Under sediment transporting conditions, the eddy diffusion coefficient is modified by a Richardson-number-based stratification correction to account for the sediment-induced stable density stratification. The correction is calculated from the local vertical concentration gradient, thus permitting von Karman’s constant to retain its clearwater value of 0.40. Also under transporting conditions, the roughness parameter Zo is increased substantially over the nontransporting Nikuradse Zo because of the extra momentum extracted from the flow by the transporting sediment. As sediment concentrations increase to large values, the bulk density and viscosity are systematically increased, causing settling velocities to decrease.


 

Acknowledgments and Associated Footnotes

1 School of Oceanography, University of Washington, Seattle, Washington 98195, USA

2 School of Oceanography, University of Washington, Seattle, Washington 98195, USA

Copyright © 2008 by the Canadian Society of Petroleum Geologists