HR: 17:55h
AN: H42K-08    [PDF]
TI: Erosion Measurements in Linear, Oscillatory, and Combined Oscillatory and Linear Flow Regimes
AU: McGovern, J J
EM: jjmcgov@sandia.gov
AF: Sandia National Laboratories, Carlsbad Programs,\break 4100 National Parks Highway, Carlsbad, NM 88220 United States
AU: Jepsen, R A
EM: rajepse@sandia.gov
AF: Sandia National Laboratories, Mechanical Environments,\break P.O. Box 5800, Albuquerque, NM 87185-1135 United States
AU: * Roberts, J D
EM: jdrober@sandia.gov
AF: Sandia National Laboratories, Carlsbad Programs,\break 4100 National Parks Highway, Carlsbad, NM 88220 United States
AU: James, S C
EM: scjames@sandia.gov
AF: Sandia National Laboratories, Geohydrology Department,\break P.O. Box 5800, Albuquerque, NM 87185-0735 United States
AB: Many contaminated sediments and dredged material mixtures of cohesive and non-cohesive sediments occur in wave-dominated environments. {\sl In situ} analysis is imperative in understanding the erosion and transport of these sediments. Recent research efforts have developed a flume with unidirectional flow that can measure {\sl in situ} sediment erosion with depth (SEDflume). However, the flow regime for the SEDflume has limited applicability to wave-dominated environments. Therefore, a unique device, called the SEAWOLF flume, was developed and used by Sandia National Laboratories to simulate high-shear stress erosion processes experienced in coastal waters where wave forcing dominates the system. The SEAWOLF is capable of testing {\sl in situ} or laboratory prepared cores. Erosion rates of cohesive and non-cohesive sediments prepared in the laboratory were determined in oscillatory and combined oscillatory and linear flow regimes. Results of these tests were compared to results from the unidirectional SEDflume. Although maximum shear stresses for oscillatory flows were as high as 7~Pa for the tests, the associated erosion rate for specific sediment over the entire wave cycle were comparable to much lower shear stresses found for constant, linear flows. For example, sediment exposed to a maximum of 7~Pa over a 15~s period resulted in erosion rates similar to results for a constant linear shear stress of 3.4~Pa. Analysis of results for all sediments tested led to a determination of values for an effective shear stress that relates wave-induced erosion to linear flow induced erosion.
DE: 1815 Erosion and sedimentation
DE: 1894 Instruments and techniques
SC: Hydrology [H]
MN: 2003 Fall Meeting