The Role of Helical and Non-Helical Drives on the evolution of Self-Consistent Dynamos
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| Format: | Preprint |
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2024
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| _version_ | 1866914879780159488 |
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| author | Biswas, Shishir Ganesh, Rajaraman |
| author_facet | Biswas, Shishir Ganesh, Rajaraman |
| contents | In the self-consistent dynamo limit, the magnetic feedback on the velocity field is sufficiently strong to induce a change in the topology of the magnetic field. Consequently, the magnetic energy reaches a state of non-linear saturation. Here, we investigate the role played by helical and non-helical drives in the triggering and the eventual saturation of a self-consistent dynamo. Evidence of small-scale dynamo (SSD) activity is found for both helical and non-helical forcing, driven at the largest possible scale. Based on the spectrum analysis, we find that the evolution of kinetic energy follows Kolmogorov's $k^-{\frac{5}{3}}$ law while that of magnetic energy follows Kazantsev's $k^{\frac{3}{2}}$ scaling. Also, we have verified that the aforementioned scalings remain valid for various magnetic Prandtl numbers (Pm). Statistical analysis is found to support our numerical finds. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2407_14810 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | The Role of Helical and Non-Helical Drives on the evolution of Self-Consistent Dynamos Biswas, Shishir Ganesh, Rajaraman Plasma Physics Astrophysics of Galaxies Computational Physics Fluid Dynamics In the self-consistent dynamo limit, the magnetic feedback on the velocity field is sufficiently strong to induce a change in the topology of the magnetic field. Consequently, the magnetic energy reaches a state of non-linear saturation. Here, we investigate the role played by helical and non-helical drives in the triggering and the eventual saturation of a self-consistent dynamo. Evidence of small-scale dynamo (SSD) activity is found for both helical and non-helical forcing, driven at the largest possible scale. Based on the spectrum analysis, we find that the evolution of kinetic energy follows Kolmogorov's $k^-{\frac{5}{3}}$ law while that of magnetic energy follows Kazantsev's $k^{\frac{3}{2}}$ scaling. Also, we have verified that the aforementioned scalings remain valid for various magnetic Prandtl numbers (Pm). Statistical analysis is found to support our numerical finds. |
| title | The Role of Helical and Non-Helical Drives on the evolution of Self-Consistent Dynamos |
| topic | Plasma Physics Astrophysics of Galaxies Computational Physics Fluid Dynamics |
| url | https://arxiv.org/abs/2407.14810 |