Hydrodynamic analyzer for sediments

The behavior of sand vary hydro-dynamically with the Reynolds Number range from 1 to 1000 for grain size and settling velocity, corresponding from laminar flow to turbulent flow. Hydrodynamic analyzer is newly developed using small inner diameter settling tubes, four sets of photo-detector, and computerized auto-handling and analysis, for the reconstruction of the sedimentary environments based on the special hydrodynamic characters of sand and sandstone. The four detectors can measure the changes in the settling velocities just after the sample is dropped and caused by the hydrodynamic interaction with small inner diameter tube. The analyzed results are shown on the computer display during the analysis. The analyzer is enough compact to use at sampling field and field station. The photo-detector is composed of high luminous emission diode and phototransistor. Logarithm of the detected signal of phototransistor corresponds well with the amount of passing sand grains. The dispersion correction is made on the detected signal for the distances from falling position to detectors. The glass beads experiments show that settling velocity can be converted to the grain-size using equations of Stokes, Allen, Karman and Newton. Two equations for the conversion are inserted into the four equations, based on the relation of the flow resistance and Reynolds Number. Using these equations, weight base contents are calculated from the detected signals. The measurements using the new analyzer show following results. 1) The grains of beach sand from the surf zone have normal distribution for the settling time, not for the logarithm of the grain size. 2) The sandstone of the submarine fan-delta sedimentary sequence in the North Fossa Magna can be classified into five types using the grain-size distribution on the logarithm of the grain size and hydrodynamic behavior. 3) Special behaviors are detected in the hydrodynamic behavior for turbidites and sediments with strong bioturbations in the submarine fan-delta sedimentary sequence.publishe