# Predicting The Flow: Math Helps Track Oil Spills

## Instead of random guessing about where the oil from a spill might end up, scientists have now created a complex model to track exactly where it (or ash from volcanoes) will go next.

In the days after the 2010 Deepwater Horizon disaster, there was a lot of conjecture about which way the spill might move. The worst-case scenario, said scientists, was for the crude to become part of the Loop Current, which would potentially take it south into the Florida Keys. But nobody could be sure. Apart from watching from the air, decision-makers had to prepare for the worst, and hope for the best.

George Haller, a mechanical engineer at McGill, hopes to be able to give more warning next time–and not only in the case of oil spills. Collaborating with another researcher at the University of Miami, Josefina Olascoaga, Haller has come up with a method of understanding the intricate internal patterns of large-scale contaminations, including oil spills, volcanic ash clouds, and tracts of oceanic plastic waste.

Haller describes the ocean as a complex swirl of “roads” and “intersections.” When flows come from opposite directions, they eject a mass of water, some of which are powerful and persistent enough to propel an oil slick in a particular direction.

By analyzing “velocity data” from thousands of points in the ocean, Haller and Olascoaga’s model is able to predict what will happen next–in the case of oil spills, up to five days in advance.

“If you look at it, it’s not obvious what’s going to happen,” says Haller. “But the research has shown there are hidden material structures in the mass that create coherence in the flow. The little fluid particles that were moving without a pattern suddenly fall in order, and start marching in the same direction.”

Haller and Olascoaga took historical data from the Gulf spill, and accurately forecast two major “instabilities” in the mass: the “tiger’s tail” that drifted toward the Loop because of shifts within the spill, and “coastal drift” that occurred because of flows coming in from the outside.

Most importantly, Haller says the research should help responders manage spills, for example by knowing where to use dispersant, and which parts of the coastline should be evacuated.