Streaky dynamo equilibria persisting at infinite Reynolds numbers

Research output: Contribution to journalArticleResearchpeer-review

Abstract

Nonlinear three-dimensional dynamo equilibrium solutions of viscous-resistive magneto-hydrodynamic equations are continued to formally infinite magnetic and hydrodynamic Reynolds numbers. The external driving mechanism of the dynamo is a uniform shear, which constitutes the base laminar flow and cannot support any kinematic dynamo. Nevertheless, an efficient subcritical nonlinear instability mechanism is found to be able to generate large-scale coherent structures known as streaks, for both velocity and magnetic fields. A finite amount of magnetic field generation is identified at the self-consistent asymptotic limit of the nonlinear solutions, thereby confirming the existence of an effective nonlinear dynamo action at astronomically large Reynolds numbers.

Original languageEnglish
Article numberR3
Number of pages11
JournalJournal of Fluid Mechanics
Volume884
DOIs
Publication statusPublished - 10 Feb 2020

Keywords

  • bifurcation
  • dynamo theory
  • high-speed flow

Cite this