Variations in Boundary Drag Coefficient in the Tidal Entrance to Chesapeak Bay, Virginia.
OLD DOMINION UNIV NORFOLK VA INST OF OCEANOGRAPHY
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Use of the quadratic shear stress law for estimating boundary drag requires specific knowledge of the magnitude of a drag coefficient, and sectional mean velocity. In previous attempts to adapt the relationship for use in marine sediment transport studies, the flow measurement has been standardized at a level 100 cm above the bed. The particularized value of the drag coefficient has been designed as C100. In the entrance area to Chesapeake Bay, Virginia, C100 has been found to range over unacceptably wide limits. Two-thirds of the values obtained are between 0.0035 and 0.054. Mean C100 for the area is 0.013 as compared to 0.003 for tidal channels within Puget Sound, Washington. Present data suggest that given a moveable bed, a size hierarchy of mobile bed forms, time varying flow, and a lack of equilibrium between flow and bed, C100 changes continuously with the flow. Accurate evaluation of boundary shear stress in tidal entrances with high flow rates and mobile beds presently requires measurement of velocity profiles. Author
- Physical and Dynamic Oceanography
- Geology, Geochemistry and Mineralogy