Sea duct : a deep-sea computer-controlled recirculating flume for the study of sea floor stability : final report

The Sea Duct Ocean-Bottom Laboratory is a computer controlled recirculating inverted flume for the in-situ study of sediment transport. It is designed to measure the sea floor response to controlled currents analogous to those generated by surface waves, tidal, or deep ocean storms. The external support frame is an equilateral triangle with sixteen foot sides. It is 12 feet high, has an air weight of 12,500 lbs., and a 2800 lb. submerged weight. Three lead acid battery packs located at the vertex of the triangle legs provide power for the recirculating water pumps, hydraulic power, and ancillary equipment. The inner rotatable structure consists of a 4 foot long by 2 foot wide open bottom windowed test section that is 9 inches high. It is connected to 30 feet of 8 inch tube configured as an elongated toroid. Above the test section is a traverse carriage with stereo camera, flash, and a laser Doppler velocimeter to measure fluid stresses. Internal flow velocities are controlled and can be ramped up to approximately 2 ft/sec providing shear stress sufficient to scour sand, silts, and fine clays. Water and sediment sampling devices obtain specimens from inside and outside the test section. This report consists of three sections. The first subdivision discusses the electro-mechanical systems and deployment- recovery techniques, while the second portion covers the microprocessor controller and its support equipment. The third section contains the appendices, which consists of program listings, schematics, system and deployment check-list, etc.Office of Naval Research, Environmental Sciences Directorate, under Contracts N00014-85-C-0001 and N00014-87-K-00