Suppression of small-scale dynamo in time irreversible turbulence
arXiv:2309.01693 · doi:10.1093/mnras/stad3191
Abstract
The conventional theory of small-scale magnetic field generation in a turbulent flow considers time-reversible random flows. However, real turbulent flows are known to be time irreversible: the presence of energy cascade is an intrinsic property of turbulence. We generalize the 'standard' model to account for the irreversibility. We show that even small time asymmetry leads to significant suppression of the dynamo effect at low magnetic Prandtl numbers, increases the generation threshold and may even make generation impossible for any magnetic Reynolds number. We calculate the magnetic energy growth rate as a function of the parameters of the flow.
References in corpus (15)
- A public turbulence database cluster and applications to study Lagrangian evolution of velocity increments in turbulence
- Numerical simulations of quiet Sun magnetism: On the contribution from a small-scale dynamo
- On magnetic field generation in Kolmogorov turbulence
- Current status of turbulent dynamo theory: From large-scale to small-scale dynamos
- Numerical demonstration of fluctuation dynamo at low magnetic Prandtl numbers
- Shell Models of Magnetohydrodynamic Turbulence
- Mean field models of flux transport dynamo and meridional circulation in the Sun and stars
- Small-scale dynamos: From idealized models to solar and stellar applications
- Hydrodynamic and hydromagnetic energy spectra from large eddy simulations
- Dynamo effect in the Kraichnan magnetohydrodynamic turbulence
- Numerical evidence for a small-scale dynamo approaching solar magnetic Prandtl numbers
- Magnetic dynamo action in random flows with zero and finite correlation times
- Long-term properties of finite-correlation time isotropic stochastic systems
- Batchelor, Saffman, and Kazantsev spectra in galactic small-scale dynamos
- Slipping flows and their breaking