Accession Number : ADA307369

Title :   Flow Measurements in a Tidal Channel Using an Acoustic Current Profiler.

Descriptive Note : Final rept. 1 Mar 93-29 Feb 96,

Corporate Author : VICTORIA UNIV (BRITISH COLUMBIA) CENTRE FOR EARTH AND OCEAN RESEARCH

Personal Author(s) : Lu, Youyu ; Lueck, Rolf G.

PDF Url : ADA307369

Report Date : 15 MAR 1996

Pagination or Media Count : 63

Abstract : An acoustic Doppler current profiler (ADCP) was applied to measure the three-dimensional flow field in a tidal channel along the coast of Vancouver Island, British Columbia. The ADCP was rigidly mounted to the bottom in the center of the channel, and rapidly sampled the velocity profiles along its inclined beams. The data were directly read by a computer on shore. This method of deployment allows for an explicit estimate of the uncertainty of mean velocity due to turbulence, and obtains the weak signal of vertical velocity. The mean flow vector is derived from the measured beam velocities under the assumption that the flow is statistically homogeneous in the horizontal plane over the distance separating the inclined beams of the ADCP. It is argued that sufficient averaging is required for flow measurements in a highly turbulent environment. The depth-time variations of velocity and shear in this natural channel are more complex than is found in idealized one-dimensional channel flow, which seldom occurs in nature. The channel contains strong secondary circulation, intense up- and down-welling intervals, frequent shear reversals and a substantial amount of transverse velocity shear.

Descriptors :   *TIDAL CURRENTS, *ACOUSTIC DETECTORS, VELOCITY, MATHEMATICAL MODELS, COASTAL REGIONS, OCEAN CURRENTS, ACOUSTIC WAVES, RESOLUTION, CANADA, TURBULENCE, TURBULENT FLOW, EDDIES(FLUID MECHANICS), DEPTH, OCEANOGRAPHIC DATA, SHALLOW WATER, FLOW FIELDS, PROFILES, ACOUSTIC MEASUREMENT, PARTIAL DIFFERENTIAL EQUATIONS, CHANNEL FLOW, OCEAN BOTTOM TOPOGRAPHY, STANDARD DEVIATION, CHANNELS(WATERWAYS), DOPPLER EFFECT, SHEAR FLOW, OCEAN TIDES, BRITISH COLUMBIA, THREE DIMENSIONAL FLOW.

Subject Categories : Physical and Dynamic Oceanography
      Acoustic Detection and Detectors

Distribution Statement : APPROVED FOR PUBLIC RELEASE