Accession Number : AD0787846

Title :   Variations in Boundary Drag Coefficient in the Tidal Entrance to Chesapeak Bay, Virginia.

Descriptive Note : Technical rept.,


Personal Author(s) : Ludwick,John C.

Report Date : AUG 1974

Pagination or Media Count : 26

Abstract : 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 C(100). In the entrance area to Chesapeake Bay, Virginia, C(100) has been found to range over unacceptably wide limits. Two-thirds of the values obtained are between 0.0035 and 0.054. Mean C(100) 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, C(100) 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)

Descriptors :   *Sediment transport, *Tidal currents, *Chesapeake Bay, Boundary layer flow, Drag, Shear stresses, Fluid flow, Velocity, Estuaries, Mathematical prediction, Density, Flow rate, Virginia

Subject Categories : Physical and Dynamic Oceanography
      Geology, Geochemistry and Mineralogy

Distribution Statement : APPROVED FOR PUBLIC RELEASE