Particle transport in the coastal bottom boundary layer using combined PIV and SVM

This dissertation is an experimental study of distribution and motion of organic and inorganic particles in the coastal ocean using submersible particle image velocimetry (PIV) and submersible video microscopy (SVM). The main purpose is to determine suspended particle kinematics in two geographical environments with different oceanographic conditions and to explore the utility of PIV for long-term measurements.; PIV images show the distribution of particles within an illuminated plane (35 cm x 35 cm). The PIV pixels are too large to resolve the size and shape of the particles. The SVM, located at the same elevation above seabed as the PIV system images particles at a resolution (480 mum x 370 mum) enables us to determine their size and shape. Hence the PIV images are used for determining the distribution of particles over a larger area, while the SVM images are used for measuring size in micro scale.; Particle properties and behavior are studied with respect to height above the sea floor, mean flow characteristics, turbulence intensity, etc. The concentration of particles increases with decreasing size down to the resolution limit of 6 mum. The PIV system "sees" different subset of particles based on their SVM measured diameter, and depends on the number of suspended particles in the water column. The PIV measured flow vertical velocity is larger than SVM estimated settling velocity of particles by two to four orders of magnitude. Horizontal advection plays a major role in transporting the particles. Most particles are nearly neutrally buoyant and they seem to be likely of biological origin transported by the mean flow. Results from both PIV and SVM are also related to the meteorological and oceanic conditions (tides, waves, T, S).; A calibration of the SVM system with other environmental instrumentation (i.e. transmissometer) widely used in the oceanographic community is essential in determining the quality of the PIV data. Ultimately, this will help to answer how environmental data can be used to estimate the utility of the PIV for long-term measurements.