Precession driven flow at large nutation angles


Precession driven flow at large nutation angles

Vogt, T.; Gundrum, T.; Giesecke, A.; Stefani, F.

Dynamos are very important, thats why we performed measurements that are motivated by a dynamo experiment currently under development at Helmholtz-Zentrum Dresden-Rossendorf (HZDR) in which the possibility of generating a magnetohydrodynamic dynamo will be investigated in a precessing cylinder filled with liquid sodium. The fluid dynamics of the precession driven dynamo experiment is investigated in a downscaled water experiment. Here, we focus on the emergence of non-axisymmetric time-dependent flow structures in terms of inertial waves which, in cylindrical geometry, form so-called Kelvin modes. Flow measurements based on Ultrasound Doppler Velocimetry (UDV) were conducted in order to identify the dominant wave modes. The azimuthal wavenumber is analyzed by four UDV transducers mounted at different azimuthal positions near the cylinder sidewall with a distance of 90° between neighbouring transducers. A radial array of six UDV transducers is utilized to resolve the radial flow structure. The aim of the work is to understand the flow structure and wave dynamics dependence on the precession ratio and to investigate their Reynolds number scalings. Besides, the results at moderate Reynolds numbers were compared to Direct Numerical Simulations and were found to be in very good agreement (see contribution from Andre Giesecke).

  • Contribution to proceedings
    2nd Conference on Natural Dynamos, 25.06.-01.07.2017, Valtice, Czech Republic
  • Poster
    2nd Conference on Natural Dynamos, 25.06.-01.07.2017, Valtice, Czech Republic

Permalink: https://www.hzdr.de/publications/Publ-25510
Publ.-Id: 25510