Accession Number:

ADA634179

Title:

Vortex Lattice Model for Mine Scour and Burial

Descriptive Note:

Corporate Author:

SCRIPPS INSTITUTION OF OCEANOGRAPHY LA JOLLA CA CENTER FOR COASTAL STUDIES

Personal Author(s):

Report Date:

1997-09-30

Pagination or Media Count:

6.0

Abstract:

LONG-TERM GOALS. We seek to understand the leading order processes and develop quantitative modeling skill for the problem of scour and burial of solid objects on a sedimentary bed in geophysical flows. OBJECTIVES. 1 Identify leading order processes 2 formulate the model and write the computer code 3 initialize and calibrate the model using archival data 4 validate the model in a contemporary field experiment with modern mines of various shapes 5 conduct numerical experiments with the model to determine the relative strength of various scour and burial mechanisms, and the sensitivity of those mechanisms to the fluid forcing history and sediment characteristics and, 6 exploit the results of the field and numerical experiments to pose potential mine countermeasures. APPROACH. Analysis of an archival data set of field measurements, photos and diver observations from a 1953-55 Mark 36 mine scour and burial experiment off Scripps Beach resulted in a model formulation with two distinct sets of burial mechanics. Separation of the model architecture into far-field and near-field burial mechanics permit the model to be adaptable to real coastal settings. The far-field mechanics Figure 1 are associated with burial due to seasonal changes in the shore rise outer and bar-berm inner bottom profiles in response to variations in the wave climate and littoral sediment supply. Seasonal bottom profile changes may cause mines to bury or become exposed, depending upon the seasonal wave climate. This is the only mechanism which can account for deep burials where the top of the mine is well beneath the ambient elevation of the bed surface, Figure 2. The seasonal profile changes are based on the second law of thermodynamics, whereby the shorerise and bar-berm profiles adjust to a change in wave climate such that they maximize the dissipation of incident wave energy.

Subject Categories:

  • Physical and Dynamic Oceanography
  • Miscellaneous Materials

Distribution Statement:

APPROVED FOR PUBLIC RELEASE