People
| Former Graduate Student | Cheng Li |
| Undergraduate Student | Jesse Miller, Evan Rodbell, Devin Conley, Anne Hosler |
| Project Supervisor | Prof. Joseph Katz |
| Design & Technical Support | Dr. Yury Ronzhes |
Dispersion of Oil Spills by Breaking Waves
Oil spilled at sea forms thin slicks, which are subsequently broken up into droplets by breaking waves. This study investigates the effects of water-oil interfacial tension and oil viscosity on the droplet size spectrum under breaking wave. Experiments are performed in a wave tank using oils with varying viscosity, along with MC252 surrogate oil premixed with the dispersant Corexit-9500A at varying dispersant to oil ratios (DOR). The breakup to droplets is visualized using high speed imaging, illustrating the generation of multiple oil-containing structures during successive splash-up cycles. Multi-resolution droplet size spectra measurements have been performed using digital holography at 11.1 and 1.1 μm/pixel. Results show that at scales expected smaller than those of the turbulence (2-10μm), the droplets are generated by micro-threading, which is strongly influenced by variations in interfacial tension. Hence, the number of such droplets is orders of magnitude higher for the DOR 1:25 and 1:100 oils. Generation of droplets larger than ~100 mm is influenced by interactions with the turbulence and by the oil viscosity. The viscosity affects the number of droplets produced, but has limited effect on the size spectrum slopes. Subsequent evolution of the size spectra is associated with differences in rise velocity, namely by variations in the the oil density and the initial droplets size.
Facility
Experimental Setup
Figure 1: Wave tank schematics and high-speed visualization set up
Figure 2: Multi-resolution in-line holography droplet size distribution measurement set up
Figure 3: PIV set up for flow field characterization
Results
Interfacial Tension Effects
Publications
Li, C., Miller, J., Wang, J., Koley, S. S., & Katz, J. (2017). Size distribution and dispersion of droplets generated by impingement of breaking waves on oil slicks. Journal of Geophysical Research: Oceans, 122(10), 7938-7957.