Non-locality of the Turbulent Electromotive Force. (arXiv:2107.10625v2 [astro-ph.GA] UPDATED)
<a href="http://arxiv.org/find/astro-ph/1/au:+Bendre_A/0/1/0/all/0/1">Abhijit B. Bendre</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Subramanian_K/0/1/0/all/0/1">Kandaswamy Subramanian</a>
The generation of large-scale magnetic fields ($overline{mathbf{B}}$) in
astrophysical systems is driven by the mean turbulent electromotive force
($overline{{cal E}}$), the cross correlation between local fluctuations of
velocity and magnetic fields. This can depend non-locally on
$overline{mathbf{B}}$ through a convolution kernel $K_{ij}$. In a new
approach to find $K_{ij}$, we directly fit the time series data of
$overline{{cal E}}$ versus $overline{mathbf{B}}$ from a galactic dynamo
simulation using singular value decomposition. We calculate the usual turbulent
transport coefficients as moments of $K_{ij}$, show the importance of including
non-locality over eddy length scales to fully capture their amplitudes and that
higher order corrections to the standard transport coefficients are small in
the present case.
The generation of large-scale magnetic fields ($overline{mathbf{B}}$) in
astrophysical systems is driven by the mean turbulent electromotive force
($overline{{cal E}}$), the cross correlation between local fluctuations of
velocity and magnetic fields. This can depend non-locally on
$overline{mathbf{B}}$ through a convolution kernel $K_{ij}$. In a new
approach to find $K_{ij}$, we directly fit the time series data of
$overline{{cal E}}$ versus $overline{mathbf{B}}$ from a galactic dynamo
simulation using singular value decomposition. We calculate the usual turbulent
transport coefficients as moments of $K_{ij}$, show the importance of including
non-locality over eddy length scales to fully capture their amplitudes and that
higher order corrections to the standard transport coefficients are small in
the present case.
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