Researchers have attempted to describe the process of swirling of wine, which has always been shrouded in mystery, in a new study.
Fluid dynamicists have long observed that orbital shaking generates a wave that propagates around the inner edge of the glass, churning the liquid as it travels.
"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," Newswise quoted Mohamed Farhat, senior scientist at the Ecole Polytechnique Federale de Lausanne in Switzerland as saying.
To figure out how the mixing occurs, Farhat and his colleagues generated such waves in clear cylinders and used state-of-the-art instrumentation to track the motion of travelling waves and measure the liquid velocity.
The researchers found that "as the wave propagates along the glass wall, the liquid is displaced back and forth from bottom to top and from the centre to the periphery," Farhat said.
"This pumping mechanism, induced by the wave, is more pronounced near the free surface and close to the wall, which enhances the mixing.
The research team also discovered that, "for a given glass shape, the mixing and oxygenation may be optimised with an appropriate choice of shaking diameter and rotation speed."