2001/06/15 by Axel Brandenburg, A. Brandenburg, B. von Rekowski +1
Biochemistry, Genetics and Molecular Biology · Physics and Astronomy · #Geomagnetism and Paleomagnetism Studies #Ionosphere and magnetosphere dynamics #Solar and Space Plasma Dynamics #astro-ph #nlin.CD
paper · pdf · doi:10.1051/0004-6361:20011400
published as Astron.Astrophys. 379 (2001) 1153-1160 · 8 pages, 10 figures, submitted to A&A
arxiv created 2001/06/15 · openalex publication_date 2001/12/01 · arxiv updated 2009/11/30 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/31
The generation of large scale flows by the anisotropic kinetic alpha (AKA) effect is investigated in simulations with a suitable time-dependent space- and time-periodic anisotropic forcing lacking parity invariance. The forcing pattern moves relative to the fluid, which leads to a breaking of the Galilean invariance as required for the AKA effect to exist. The AKA effect is found to produce a clear large scale flow pattern when the Reynolds number, , is small as only a few modes are excited in linear theory. In this case the non-vanishing components of the AKA tensor are dynamically independent of the Reynolds number. For larger values of , many more modes are excited and the components of the AKA tensor are found to decrease rapidly with increasing value of . However, once there is a magnetic field (imposed and of sufficient strength, or dynamo-generated and saturated) the field begins to suppress the AKA effect, regardless of the value of . It is argued that the AKA effect is unlikely to be astrophysically significant unless the magnetic field is weak and is small.