Kazantsev dynamo in turbulent compressible flows

• Type: Article in International Scientific Journal
• Date: 2019

Authors

Afonso, MM (Author) FCUP; Mitra, D (Author) Other; Vincenzi, D (Author) Other

Journal

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

Vol. 475

ISSN: 1364-5021

Publisher: The Royal Society

Indexing

ISI Web of Knowledge - 1 Citation

Scopus - 3 Citations

Other information

Authenticus ID: 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.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 17