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Turbulent Rayleigh-Benard Convection

Convection

The image is a visualization of a turbulent Rayleigh-Benard convection flow in a cylindrical cell with aspect ratio one. This is the typical setup in many laboratory experiments. The temperature difference between the hot bottom plate and the cold top plate drives and sustains the turbulent motion in the cell. The side walls are thermally isolated.


The image shows the region which is close to the heated bottom plate.  The structures of the velocity field are visualized. In detail we show so-called streak lines (Streichlinien). It can be seen how the hot fluid moves up with a large upward velocity (red color of the lines). All the streak lines form a very complex skeleton which is permanently in motion. These red colored segments of the streak lines are a fingerprint of so-called thermal plumes (hot blobs of fluid). Close to the side wall such plumes can also merge in form of two mini tornados. An interesting potential application are so-called "dust devils" which are observed in the atmospheric boundary layer (and could probably studied in laboratory under controlled conditions). Their appearance is not yet understood.

Data: Jörg Schumacher, TU Ilmenau
Visualization: Herwig Zilken, Forschungszentrum Jülich, JSC