Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

2 Publications
Experimental study of the suppression of Rayleigh--Benard instability in a cylinder by combined rotating and static magnetic fields
Grants, I.; Pedchenko, A.; Gerbeth, G.;
We consider experimentally transitions in a liquid metal cylinder heated from below and subject to superimposed rotating and static magnetic fields. Being itself unstable, a strong enough rotating magnetic field driven flow suppresses considerably the temperature fluctuations due to the thermo-gravitational convection. The remaining fluctuations are caused by unsteady Taylor vortices generated near the side wall. Our experiment shows that the superimposed static `cusp' field further reduces the amplitude and characteristic period of these remaining temperature fluctuations while a superimposed uniform axial field has no such effect. The observed behavior agrees quantitatively with the differing effects of various static fields on the additional unstable Taylor vortex type solutions, which bifurcate sub-critically and actually govern the transition in the RMF driven flow. Thus, the observations are consistent with the description of a turbulent shear flow as a trajectory wound irregularly on the skeleton of the additional unstable flow states. If this `skeleton' is compressed by an external influence (the `cusp' static field in our case), then also the averaged amplitude of turbulent fluctuations decreases by the same factor.
  • Physics of Fluids 18(2006), 124104
  • Lecture (Conference)
    2nd International Symposium "Instabilities and Bifurcations in Fluid Dynamics", 15.-18.08.2006, Copenhagen, Denmark

Publ.-Id: 8352 - Permalink