Saturday, January 30, 2010

Chemistry Drives Convection

There's a short article with a neat set of flow-viz pictures and a movie on the APS site. It's kind of funny how research results get written up in the popular press.
As a demonstration of the chemistry "tail" wagging the fluid dynamics "dog," researchers have...
Although this chemically-induced convection was not a surprise, the convection patterns in the simulations were surprising. In some cases the convective plumes went only upward from the boundary, rather than creating a symmetric pattern that sent fingers both up and down from the mid-line.
It turns out that even without a chemical reaction, convection would be expected if the reactants had different diffusion rates.
The new simulations show that convection makes the reactions progress faster, just as stirring would.
I'm not sure how surprising any of that would be. Turbulent mixing is a well known way of increasing reaction rates, for instance in flame-holders and high-g combustors. It's also kind of funny how everything has to do with climate change:
This could mean that researchers have underestimated reaction and mixing rates in natural phenomena, like the Earth's mantle and supernova explosions, as well as for carbon sequestration, in which carbon dioxide is stored underground. Modelers have so far not considered how convection induced by the interaction of carbon dioxide with ground water may affect the long-term containment of this greenhouse gas...
Now that's the funding tail wagging the science dog.

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