Date of Award

Spring 2017

Project Type

Thesis

Program or Major

Civil Engineering

Degree Name

Master of Science

First Advisor

Nancy E Kinner

Second Advisor

Kenneth Baldwin

Third Advisor

Thomas P Ballestero

Abstract

Under certain environmental conditions and depending on its specific gravity, spilled oil has the ability to sink to the bottom of a water body (e.g., lake, river, ocean) (i.e., sunken oil). Once there, it can be difficult to predict the sunken oil’s fate and transport, making response efforts challenging. The Office of Response and Restoration (ORR) of the National Oceanic and Atmospheric Administration (NOAA) currently uses mathematical models in an attempt to better predict the movement of spilled oil. However, mathematical models cannot be simulative of the predicted trajectory if the physical or chemical properties of the oil are unknown, which limits the effectiveness for response. This is especially true for models predicting the movement of sunken oil.

The critical shear stress (CSS) of sunken oil is the key parameter that governs whether it will migrate along the bottom of a water body or become resuspended in the water column. Ideally, there would be CSS estimates for all oil types that responders could reference during a spill, but research in this field is limited. This thesis research, conducted by the Coastal Response Research Center (CRRC) at the University of New Hampshire (UNH), used an annular flume equipped with an acoustic Doppler velocimeter and high definition cameras, to estimate the CSS of Alberta bitumen by measuring instantaneous, three-dimensional water current velocities.

For this thesis, CSS estimates of Alberta bitumen were calculated using 21 saltwater runs and 15 freshwater runs. Runs were performed at varying temperatures (15.7-28°C) and water velocities (8.5-60 cm/s; 0.17-1.2 knots). Mathematical CSS estimates were determined using MATLAB. Shear stress estimates ranged from 0.06-2.32 Pa, which are comparable to those determined by other researchers at the velocity range tested in this research. Results showed that higher temperature and water velocity resulted in increased sunken oil movement; no significant trends were observed for sunken oil erosions.

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