'Tears of wine' flowing through a glass may be born by a shock wave

by chispita_ 666

After lightly turning the wine-poured glass, you can observe how the phenomenon that the wine's droplet rises inside the glass and flows like tears is observed repeatedly. " Tears of wine for the identity of this mysterious phenomenon called", of Andrea Bertozzi Mr. American Physical Society is the mathematics, engineering, aviation mechanics professor of the University of California - Los Angeles 2019 annual physics conference in, "the formation of the wine of tears We have made a presentation that overturns the established theory that "a special shock wave is involved ."

APS - APS March Meeting 2019 - Event - Tears of wine and shock dynamics
http://meetings.aps.org/Meeting/MAR 19/Session/E 56.12

Why is your wine crying? Scientists say shock waves likes play a role | Ars Technica
https://arstechnica.com/science/2019/03/why-is-your-wine-crying-scientists-say-shock-waves-likely-play-a-role/

You can see how the phenomenon of wine tears actually is by seeing the following movie.

Marangoni Effect: Tears of Wine (and Rum) - YouTube


As the wine rises so that it can be drawn up through the inside of the glass, it becomes droplets when a certain amount accumulates, and flows down according to gravity. When watching the glass from the side, the wine keeps flowing just like tears.

Studies on tears of wine have existed for a long time and it is said that in 1855, British physicist James Thomson was the first scientist to pay attention to wine tears. Many physicists have tried over 150 years on the question of "why tears of wine is born", and as a result, "The tears of wine are caused by the physical phenomenon of Marangoni convection " is a modern theory.

Marangoni convection is a flow that is created by changing the surface tension of a liquid due to temperature differences and the like. In general, the surface tension decreases when the temperature is high, and the surface tension increases when the temperature is low. Therefore, the balance of the surface tension collapses and the phenomenon "a liquid flows from a high temperature to a cold place" occurs.

" Coffee ring effect " is said to be involved in this Marangoni convection by a familiar phenomenon. This effect is thought to occur because coffee particles gather and dry on the outer periphery due to Marangoni convection because of the phenomenon that when the spilled coffee dries, only the outline of the coffee becomes darker.

by Jacob Gube

Wine basically consists of water and alcohol. Capillary phenomenon will cause the wine to rise above the liquid level along the wine adhering to the inside of the glass, but alcohol is accumulated in wine and glass adhering to the inside of the glass because the vapor pressure is higher than water A difference in the concentration of wine is born, and Marangoni convection causes a flow of wine going up along the inner wall of the glass. And the theory that modern day's idea that wine tears flowing as droplets by self weight when exceeding a certain amount is a wine tear.

by Gabriela Gordon

However, recent research suggests that problems that can not explain the formation of wine tears have emerged with Marangoni convection alone. For example , in the survey of 2015, it was found that gravity, room temperature, heat of vaporization due to evaporation of alcohol also greatly affected the formation of tears of wine, and with warm Marangoni convection alone, wine influenced gravity It seems that it is understood that it is insufficient to explain the phenomenon of shaking off the inner wall of the glass.

So Mr. Bertozzi observed the state of dropping silicone oil on a glass plate and heating it. The upper surface of the heated oil is cold and the lower surface becomes warm, but it seems that a small wave of oil is generated on the plate at this time. Mr. Bertozzi calls this wave "low compression shock wave" and argues that this is an important element for forming wine tears.

According to Bertozzi, this shock wave is caused by the gradient of surface tension. To verify the hypothesis, the research team led by Mr. Bertozzi pour port wine into martini glass and observed with a slope of 65 degrees. As a result, it was confirmed that the same wave as the silicone oil on the plate was transmitted to the wine inside the glass, and finally the tears of the wine were also observed.

by fs999

"We were able to create an abnormal wave that rose to the gravity and move on the plate.When the tears of the wine were observed, this low compression shock wave has a big influence on its formation "Our research team thinks," Bertozzi said and said he plans to do further experiments to find out how complex dynamics are involved behind the tears of wine.