Fluid that is sufficiently heated from below and cooled from above is known as Rayleigh–Bénard convection (RBC) and has been at the center of scientific inquiry for a long time [1]. RBC serves as a model system for buoyancy driven convection and can be found in numerous astrophysical, geophysical, atmospheric, and industrial processes.

A schematic of a cylindrical RBC cell is depicted in figure 1. When the temperature difference Δ between the plates is large enough, the fluid enclosed by the cylinder will start to transport heat by buoyancy induced convection in addition to conduction. The temperature difference can be expressed in non-dimensional form by the Rayleigh number Ra and is a measure of the system's driving strength. Likewise, the resulting heat flux that passes through the plates and the fluid can be expressed by the non-dimensional Nusselt number Nu. One important question is the dependence of Nu(Ra).

Figure 1:

A schematic of a cylindrical Rayleigh-Bénard convection (RBC) cell with diameter D and length L. The warm bottom plate is at an excess temperature Δ with respect to the cold top plate at temperature T0. When the temperature difference Δ between the plates is large enough, the fluid enclosed by the cylinder will start to transport heat by convection in addition to conduction.


In our group we study several topics on heat convection. They involve:
  · Turbulent RBC and the ultimate-state transition
  · Rotating RBC
  · Moist turbulent convection
  · Inclined layer convection

To experimentally investigate turbulent heat convection at high Ra numbers our group features the Göttingen "U-Boot".



References

[1] G. Ahlers, S. Grossmann, and D. Lohse, Rev. Mod. Phys. 81, 503 (2009)