Turbulent convection in liquid metals at large Rayleigh numbers

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Turbulent convection in an eutectic Gallium-Indium-Tin (GaInSn) alloy at a very low Prandtl number of Pr=0.023 is jointly studied in laboratory experiments and numerical simulations. For the first time, velocity measurements with arrangements of multiple ultrasound sensors as well as a reconstruction by means of magnetic field tomography will reveal the velocity field structure in the near-wall regions and in the bulk of the cylindrical convection cell for Rayleigh numbers up to 2e9. The measurements will provide for the first time data on the global momentum transfer and the long-time behavior of the 3d large-scale structure. They are backed up by massively parallel spectral element simulations with a focus to the full 3d boundary layer dynamics and the impact of non-ideal thermal boundary conditions at the heated and cooled plates on momentum and heat transfer. The simulations will also help to interpret the measured turbulence statistics. The joint investigations set a new milestone for a deeper understanding of turbulent convection at very low Prandtl numbers with its numerous applications in geo- and astrophysical flows as well as in technological systems.