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Evolution of helicities in dynamo problems

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Abstract

The properties of wavelet spectra of kinetic and magnetic energies, as well as of helicities, are considered by the example of a three-dimensional dynamo model in a rapidly rotating a plane layer and heated from below. It is shown that the transition from the kinematic mode to the full dynamo mode is accompanied by a decrease in the magnetic energy of the system. The hydrodynamic helicity changes its sign by height and has the same sign for all scales. The current and magnetic helicities also have the dipole form of symmetry in the physical space; however, their sign at small and large scales is different—the so-called effect of separation in scales. The cross-helicity has no separation in scales, but it can change the sign with time so that its averaged value is small.

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Correspondence to M. Yu. Reshetnyak.

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Original Russian Text © M.Yu. Reshetnyak, 2015, published in Doklady Akademii Nauk, 2015, Vol. 463, No. 3, pp. 276–280.

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Reshetnyak, M.Y. Evolution of helicities in dynamo problems. Dokl. Phys. 60, 283–287 (2015). https://doi.org/10.1134/S1028335815060038

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  • DOI: https://doi.org/10.1134/S1028335815060038

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