At left, highly turbulent behavior as water flows into (clear) oil. At right, all turbulence is suppressed by using cornstarch. | Department of Energy Photo | Courtesy of Lawrence Livermore National Laboratory | Public Domain
Bachelor kitchens are rarely known for their cleanliness. One reason is that bachelors can make a complete meal of condiments. Another is that when faced with a sudden spill, bachelors become instant innovators, grabbing anything within arms reach, whether paper towels, dirty socks or even cornstarch, to stem the flow of liquid.
In a sense, it's not that different from the challenge recently faced by researchers at the Department of Energy’s Lawrence Livermore National Laboratory (LLNL) when they set out to find the proper mix of fluids needed to cap the powerful flow of oil that can occur during a spill, an objective that was principally driven by the failure of the top-kill method during last year's oil spill in the Gulf of Mexico.
As may be remembered, the top-kill attempted to plug the gusher by forcing heavy mud down the hole. However, the upwards rushing oil and resulting turbulence between the two liquids (technically called a Kelvin-Helmholtz instability) broke the mud up well before it could form a seal.
A fluid that compresses under stress – similar to a group forming an informal phalanx when going upstream – stands a much better chance of making it to its destination. That’s what LLNL researchers composed, a ‘shear-thickening’ liquid that can force its way through the turbulence of oil moving in the opposite direction. Its secret ingredient? Cornstarch.Anyone who has tried to keep a group together in a busy subway station can appreciate the difficulties caused by Kelvin-Helmholtz instabilities. The crowd pushing past in the opposite direction breaks up the group, inevitably and irrevocably separating them from the one person who actually knows where they’re going.
The cornstarch mix flows easily under normal conditions, but thickens when shaken, suppressing turbulence. After creating their new fluid, LLNL researchers then tested it in a tank of oil at speeds comparable to the Gulf gusher. They found that the starchy mix held steady, descending to the bottom of the column without breaking.
Should another spill come, it’s unlikely that helicopters will be flying over; dropping giant boxes of Argo and Kingsford’s finest. But the starchy success does give scientists and engineers a better sense of how to respond to future crises. It also gives them more insight to fundamental fluid forces, since the LLNL researchers published their work in the Jan. 31 issue of Physical Review Letters.
Each day, researchers at the Department of Energy and its National Labs are working on new innovations and finding ways to clean up messes on a scale even bachelor ‘cooks’ have never imagined.
For more information on the DOE Office of Science, please go to: www.science.energy.gov.