Under pressure: studying cloud-like turbulent superstructures

Turbulent superstructures occur everywhere, such as in the clouds, in eddies in the ocean, or on Jupiter with its red spot. Understanding their dynamic flow is important for making weather and climate predictions and much more.

Yik et al. described using their high-pressure vessel known as the “Uboot of Göttingen” to investigate turbulence. While the Uboot is not new, they reported a new method to investigate turbulent superstructures driven by thermal convection at high turbulence levels.

Author Eberhard Bodenschatz has always been fascinated by periodic structures of nature. He wonders how highly turbulent structures self-organize and create patterns. He thinks of giant stratocumulus clouds and marvels at the repeating ridges they naturally form despite the disorder within.

“Clouds are the most turbulent structures on Earth,” said Bodenschatz.

In their study, Bodenschatz and his colleagues used a heavy gas, sulfur hexafluoride (SF₆), in the Uboot pressurized system. Installed within the Uboot is a rectangular convection cell called the Long High Pressure Convection Facility (LHPCF). This Rayleigh-Bénard convection cell controls temperature very precisely, allowing for spatially-resolved heat flux measurements. Temperature control comes from multi-layered heating plates above and below the chamber. With about 350 temperature sensors, the apparatus can closely monitor the temperature in the chamber.

With this system, the team experimentally realized superstructures at levels of turbulence not reachable with the fastest supercomputers. Previously, experiments were limited to only one overturning roll, while their experiment allowed for more. Furthermore, the system has clear, plexiglass walls, giving researchers the ability to track particle movement in future experiments.

“Future work plans are to put small particles in the system and then track them with cameras to see the motion of the fluid,” said Bodenschatz.

Source: “A multipurpose thermal convection setup to study turbulent super structures,” by Hiufai Yik, Constantin Schettler, Eberhard Bodenschatz, Umesh Madanan, and Stephan Weiss, Review of Scientific Instruments (2026). The article can be accessed at https://doi.org/10.1063/5.0347966 .