Kazantsev dynamo in turbulent compressible flows

• Tipo: Artigo em Revista Científica Internacional
• Data: 2019

Autores

Afonso, MM (Autor) FCUP; Mitra, D (Autor) Outra; Vincenzi, D (Autor) Outra

Revista

Título: Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences

Vol. 475

ISSN: 1364-5021

Editora: The Royal Society

Indexação

ISI Web of Knowledge - 1 Citação

Scopus - 3 Citações

Outras Informações

ID Authenticus: P-00Q-FC5

DOI: 10.1098/rspa.2018.0591

Abstract (EN): We consider the kinematic fluctuation dynamo problem in a flow that is random, white-in-time, with both solenoidal and potential components. This model is a generalization of the well-studied Kazantsev model. If both the solenoidal and potential parts have the same scaling exponent, then, as the compressibility of the flow increases, the growth rate decreases but remains positive. If the scaling exponents for the solenoidal and potential parts differ, in particular if they correspond to typical Kolmogorov and Burgers values, we again find that an increase in compressibility slows down the growth rate but does not turn it off. The slow down is, however, weaker and the critical magnetic Reynolds number is lower than when both the solenoidal and potential components display the Kolmogorov scaling. Intriguingly, we find that there exist cases, when the potential part is smoother than the solenoidal part, for which an increase in compressibility increases the growth rate. We also find that the critical value of the scaling exponent above which a dynamo is seen is unity irrespective of the compressibility. Finally, we realize that the dimension d = 3 is special, as for all other values of d the critical exponent is higher and depends on the compressibility.

Idioma: Inglês

Tipo (Avaliação Docente): Científica

Nº de páginas: 17