Wednesday, October 16, 2013


Howdy! My name is David Murphy, and I’m a postdoctoral fellow in Mechanical Engineering at Johns Hopkins University. I’m working with the other DROPPsters here at Hopkins (and across the world!) to study how oil spreads out in the ocean once it is spilled. It is important to understand how the oil breaks up into smaller and smaller blobs so that we can understand where it will eventually end up. Oil in the ocean can be dispersed due to many different environmental forces, such as currents, turbulence in the ocean, waves on the surface, and mixing created by swimming animals. Here at Hopkins we do experiments to simulate these mixing events in the laboratory so that we can better predict where the oil will go.
In this picture, you can see several of the tanks where we do experiments. The large tank on the right contains an oil/water mixture from one of my experiments.
In order to make our experiments as realistic as possible we are using real crude oil from the Gulf of Mexico. Crude oil is NASTY stuff! It is dangerous since it is flammable; it is also volatile, which means it gives off hazardous fumes. In order to keep us safe, we have a high-powered ventilation system to remove the fumes and fireproof cabinets where we store the oil. We also wear gloves to protect our skin.
The fireproof cabinet where we store the crude oil
Of course, once we have completed an experiment, we have to clean up. One of the things I’ve learned as a DROPPster is that oil is hard to clean up! It takes a lot of work to clean out our tanks after doing an experiment, and this makes me sympathize with the folks cleaning up oil on the beaches and in the marshes after a real oil spill. As we clean up in the lab, we can’t drain the oily water into the sewer, so we have a skimmer that separates the oil from the water. We can then collect the oil and dispose of it properly.

The skimmer and oil barrel where we collect oil after an experiment

Cleaning up after an experiment in our sink that drains to the skimmer
Finally, I want to give a little taste of what oil looks like when it is mixing with water. In the video below, oil that has been mixed with dispersant is leaking out of a nozzle to form a plume. This simulates oil rising from an oil well blowout on the bottom of the ocean. Like dish soap, dispersant reduces the interfacial tension between the water and the oil and allows the oil to break up into tiny droplets that will disperse in the ocean more easily. We’re studying how dispersant interacts with environmental flows to promote oil dispersal.


video