Graduation Year

2022

Document Type

Dissertation

Degree

Ph.D.

Degree Name

Doctor of Philosophy (Ph.D.)

Degree Granting Department

Mechanical Engineering

Major Professor

David W. Murphy, Ph.D.

Committee Member

Rasim Guldiken, Ph.D.

Committee Member

Andres Tejada-Martinez, Ph.D.

Committee Member

Gary Mitchum, Ph.D.

Committee Member

Srijan Aggarwal, Ph.D.

Keywords

Arctic, Contraction, Ice, In situ burning, Oil spill, Particle image velocimetry

Abstract

Chemical herders are a promising technique for treatment of oil spills in icy waters at high latitudes. However, obstacles on the water surface such as floating ice affects or interferes with all spill response countermeasures including chemical herder operations by fracturing the contracting oil slick and trapping small oil patches. Chemical herders are likely to be especially useful in containing oil spills in remote, ice-infested Arctic waters, where using booms to contain an oil slick is difficult. Much of the previous research into chemical herder has focused on the effectiveness of different types of chemical herder agents to thicken oil slicks (Garrett and Barger, 1972; Potter et al., 2016), windows of opportunity to enhance the in-situ burning response (Bullock et al., 2017), scaling up laboratory experiments to the field, oil types and weathering state (Buist et al., 2011; Byrne et al., 2018; Rojas-Alva et al., 2019), applying the herder before or after the oil slick spreading (i.e. pre- or post-treatment) (Buist et al., 2011; Buist et al., 2008; Buist et al., 2007), herder effectiveness in open and ice-covered water (van Gelderen et al., 2017; Buist et al., 2018), and sea conditions (e.g., salinity, temperature, wave, and wind) (Potter et al., 2016; van Gelderen et al., 2017). However, the fluid physics of why and how much oil is retained by these obstacles as the herding agent moves the oil slick across the water surface is not currently understood. Factors such as obstacle size and shape, slick properties, slick retraction speed, and density of obstacles likely play influential roles.

In this study, I aim to explore the fluid dynamics of the oil slick contraction under the influence of chemical herding agent using a 2D visualization system. This system enables us to quantitatively visualize in 2D the spreading of crude oil on the water surface and the subsequent contracting and thickening of oil slick after chemical herders are released. Moreover, I vary the obstacles’ size, shape, pack density, and gap width in order to examine their effects on the contraction of the oil slick in a laboratory scale basin using Alaska North Slope crude oil and OP-40 herding agent at room temperature (25 °C – 28 °C). More specifically, I present measurements of oil slick area, thickness, contraction speed, spatial distribution, and surface distribution of the herded oil slick, at several time points. Further, I calculate the spreading of thin liquid films (e.g., oil slicks and monomolecular surface films) on the water surface and compare the result with previous studies. Finally, I use particle image velocimetry (PIV) to measure the flow of the oil slick around the obstacles.at several time points

Understanding the fluid dynamics and fragmentation of the herded slick in response to the presence of obstacles on the water surface could lead to novel techniques for applying chemical herder which will enhance herder efficiency or in-situ burning. For example, herder application could be tuned in order to minimize the fracturing of the oil slick and to determine the time at which slick ignition would be most appropriate, thus leading to better chemical herder effectiveness and decreased environmental harm from the oil spill. In addition, we have used PIV to measure the flow and thickening of a contracting oil slick and its interaction around with obstacles for the first time. This technique may prove useful for measuring oil slick motion in the field in the future.

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