Growth of magnetic fluctuations in a turbulent flow (Q2712927)

The author presents a kinematic MHD dynamo theory for turbulent conductive fluids, starting from incompressible flows. The evolution of magnetic noise is considered on a timescale much larger than the correlation time of fluctuating flow. Magnetic fluctuations are generated below the viscous scale of turbulence, and the velocity field is approximated by a linear profile. At small scales no folding of magnetic field occurs, only stretching and contraction. The spatial smoothness of velocity allows a systematic analysis of Lagrangian path dynamics and allows to study a respective evolution of magnetic field. The behaviour of magnetic field is approximated for small yet finite diffusivity. The field is shown to be concentrated in narrow strips. Additionally, the author desribes anomalous scalings and angular singularities of multi-point correlation functions, which can be interpreted as manifestations of field intermittency. The growth rate of Lyapunov spectrum is considered both for incompressible and compressible fluids, and it is shown that the magnetic flux always decays at large times.NEWLINENEWLINEFor the entire collection see [Zbl 0952.00057].