Date of Award

Spring 2024

Project Type

Thesis

Program or Major

Civil Engineering

Degree Name

Master of Science

First Advisor

Nancy E Kinner

Second Advisor

James P Malley, Jr

Third Advisor

Tracy L Mandel

Abstract

Oil spilled into marine or freshwater environments can become submerged in the water column or sink to the bottom if its density is greater than that of water. Meso-scale experiments were conducted in the Coastal Response Research Center’s (CRRC) MacFarlane Flume at the University of New Hampshire (UNH) to better understand sunken oil transport in a river environment. Flume water temperatures reflected the annual range of the Mississippi River’s temperatures near Baton Rouge, LA (41 °F to 86 °F), a location where a spill is likely to occur because of shipping traffic. Flat and scaled sand dune substrates were secured to the bottom of the flume and sunken oil was injected onto them. The sand was a medium size (d50 = 0.017 in) and had similar dimensions to that of the Lower Mississippi River (0.016 +/- 0.009 in) (Thorne et. al., 2017). English units will be used throughout this thesis, as these are most familiar to U.S. spill responders. No. 6 Heavy Fuel Oil (HFO) (24% kaolinite clay by mass) and very low sulfur heavy fuel oil (VLSHFO) (40% kaolinite clay by mass) were used for these experiments. Flume water velocities were increased in 0.16 knots intervals, until the oil moved off the substrate. Acoustic Doppler velocimeter (ADV) measurements were used to determine critical velocities and critical shear stress. This analysis determined: (1) the critical velocities and CSS at 41 °F were higher than at 86 °F, (2) the scaled bedforms did not affect critical velocity or CSS, (3) the VLSHFO at 41 °F had a higher critical velocity and CSS than the No. 6 HFO, and (4) the oil type did not affect critical velocity and CSS at 86 °F. At 86 °F, the oil exhibited gravity spreading, rope formation, and droplet resuspension. At 41 °F, the oil rolled along the substrate in a mound shape. These results help inform oil spill trajectory modeling predictions by providing information about when and how sunken oil may move.

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