# Oenodynamics: The Physics of Wine Swirling

Oenophiles, or wine enthusiasts, use a technique to bring out the best taste in their red wines swirling their wine glasses before sipping. A new fluid dynamics study by Martino Reclari et al at the École Polytechnique Fédérale de Lausanne in Switzerland has revealed the physics and fluid dynamics behind that sloshing, or oenodynamics.

Swirling a wineglass gently creates smooth arcs in the liquid that then circle, coating the sides of the glass. Scientists and enthusiasts alike have long known that the swirling motion mixes oxygen into a red, enhancing its flavor. Swirling too quickly results in nodes and ant-nodes, or crests and troughs. Under certain conditions, the wine wave can “dry” the sides of the glass, or the wine can splash. According to these Swiss oenodynamic physicists, there are three unit-less factors that may determine whether your merlot arcs smoothly or starts to splash:

1. $\vec{d_s}=d_s / D$ , where D  is the inner diameter of the wine glass, $d_s$ is the diameter of the swirl action
2. $\vec{H_0}=H_0/D$ , where $H_0$ is the elevation of the liquid at rest
3. $Fr^2=\omega d_s/g$ , where $\omega$ is angular velocity of the swirl

“The breaking acceleration for a merlot is about 40% of the force of gravity, the team concluded, or nearly 4 meters per second. That acceleration, in turn, is dependent on the volume of wine in the glass, the force of shaking, and other factors.”

Given the following: D = 0.144 m, ds = 0.0125 m, H0 = 0.075 m, and w = 120 rpm we get only one crest. Given D = 0.287 m, ds = 0.05 m, H0 = 0.15 m, and w = 80 rpm, we get two crests. The video shows various iterations, with the key takeaway being that swirling the wine does indeed change the oxygenation levels, which in turn affects taste.

Aerospace Cubicle Engineer