November 23, 2011
Researchers Determine Why Wine Aeration Works
Researchers have determined how the process of swirling wine around in a glass to aerate the liquid actually works.
The team generated waves in clear cylinders and used state-of-the-art instrumentation to track the motion of traveling waves and measure the liquid velocity.
The team found that "as the wave propagates along the glass wall, the liquid is displaced back and forth from bottom to top and from the center to the periphery," Mohamed Farhat, senior scientist at the Ecole Polytechnique Federale de Lausanne in Switzerland, said in a press release.
"This pumping mechanism, induced by the wave, is more pronounced near the free surface and close to the wall, which enhances the mixing."
The process of "orbital shaking" has been a mystery to fluid dynamicists, who have long observed that swirling the wine generates a wave that propagates around the inner edge of the glass.
"The formation of this wave has probably been known since the introduction of glass or any other kind of cylindrical bowl, but what has been lacking is a description of the physics related to the mixing and oxygenation," Farhat said in a press release.
The team also discovered that to maximize aeration, one must find an appropriate choice of shaking diameter and rotation speed for each glass.
Farhat said that the new work demonstrates that the bioreactors in wine "offer better mixing and oxygenation over existing stirred tanks, assuming that operating parameters are carefully optimized."
"The gentle nature of orbital shaking also ensures a better viability and growth rate of the cells at reduced cost," he said in a press release.
The researchers explained their findings in a talk at the American Physical Society's Division of Fluid Dynamics Meeting on Monday, Nov. 21.
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