Feedback of a small-scale magnetic dynamo.
We develop a WKB approach to the rapid distortion theory for magnetohydrodynamic turbulence with large magnetic Prandtl number. Within this theory, we study the growth of small-scale magnetic fluctuations in a large-scale velocity field being initially a pure strain. We show that the magnetic Lorentz force excites a secondary flow in the form of counterrotating vortices on the periphery of the magnetic spot. Those vortices slow down stretching of the magnetic spot and thus provide a negative feedback for a small-scale magnetic dynamo.
Nazarenko
S V
SV
Mathematics Institute, University of Warwick, Coventry CV4 7AL, United Kingdom.
Falkovich
G E
GE
Galtier
S
S