What are some tricks in fluid dynamics

When Paul Linke at home in Kemnitz throws a water bottle on the kitchen table in a somersault over and over again, the parents don't doubt their son's brains. Because what Paul is doing is a physical experiment. And with his way of spinning the bottle, the 18-year-old high school graduate from Löbauer Geschwister-Scholl-Gymnasium has come a long way. Paul Linke and four other high school students form the German team at the International Young Physicists Tournament (IYPT) in Beijing. The international tournament for young physicists is considered the physics world championship.

"Fortunately, some parameters spoke for me," said Paul Linke, scientifically cautious, on his success, in which his high school colleagues Fabian Bartuschk from Oppach and Christoph Seibt from Zittau also participate. The three have formed the “C4LQL83D” physics competition team at Geschwister-Scholl-Gymnasium for two years. That reads complicated at first, but on closer inspection it can be deciphered as the English word "CALCULATED" and simply means "calculated" in German. "We chose this name because the competition has a lot to do with math problems," says Paul Linke.

The last competition was the German preliminary round for the IYPT in February in Bad Honnef, North Rhine-Westphalia. The Löbauer team took a top position. And after another test weekend of the top ten participants at Ulm University, Paul Linke was confirmed as a member of the German team for Beijing. Uwe Kopte, head of the department for mathematical and scientific subjects (MINT subjects) at the grammar school, sees the success as the provisional high point of the excellence initiative of the Geschwister-Scholl grammar school. "The three belong to the first year who started their in-depth mathematical and scientific training here," says Kopte. And the young physicists achieved this success in many hours of experimentation in addition to their actual work for the Abitur - for example by throwing the bottle. "We repeated the bottle flip thousands of times, with different bottles," says Paul Linke, "here at school and also at home."

This experiment, which is also important for the physics world championship, is about something that many people have already observed in everyday life: if you throw a partially filled plastic bottle in a somersault, it often does not fall over, but straightens up again. Under what circumstances and why this is so - that is what the participants at the physics world championship should scientifically derive and justify in front of a jury of experts. The rotational movement of the bottle, the movement of the water or the deformation of the bottle upon impact are physically significant. Paul Linke calls it “turbulent currents” or “translational energy” and finally. “I have set up a theory,” says Paul Linke, “the filling level should correspond to the diameter of the bottle.” Such theories must then be proven in competition and scientifically substantiated.

"With school resources, you reach your limits very quickly," says department head Uwe Kopte. Some of the computing power required for this would keep a computer busy for days, for example. But the research group at the Geschwister-Scholl-Gymnasium received scientific help. "We got professional advice at the Helmholtz Center in Dresden-Rossendorf," says Paul Linke. There are experts in "fluid dynamics", that is, for the flow behavior of liquids. And the Department of Electrical Engineering and Physics at the Zittau-Görlitz University of Applied Sciences provided experimental support with high-quality measurement electronics.

Paul Linke is now hoping for success in Beijing, but he is also sticking to the Olympic motto: "Being able to take part in the Physics World Cup is already an award on your CV," he says. Because even after graduating from high school, he is aiming for a scientific career as a physicist. The World Cup could be a top application: "That's where international universities are behind the competition and that's where many universities are looking."