Bibcode
Popescu Braileanu, B.; Lukin, V. S.; Khomenko, E.; de Vicente, Á.
Bibliographical reference
Astronomy and Astrophysics, Volume 627, id.A25, 18 pp.
Advertised on:
7
2019
Journal
Citations
47
Refereed citations
47
Description
Solar chromosphere consists of a partially ionized plasma, which makes
modeling the solar chromosphere a particularly challenging numerical
task. Here we numerically model chromospheric waves using a two-fluid
approach with a newly developed numerical code. The code solves
two-fluid equations of conservation of mass, momentum, and energy,
together with the induction equation for the case of the purely hydrogen
plasma with collisional coupling between the charged and neutral fluid
components. The implementation of a semi-implicit algorithm allows us to
overcome the numerical stability constraints due to the stiff
collisional terms. We test the code against analytical solutions of
acoustic and Alfvén wave propagation in uniform medium in several
regimes of collisional coupling. The results of our simulations are
consistent with the analytical estimates, and with other results
described in the literature. In the limit of a large collisional
frequency, the waves propagate with a common speed of a single fluid. In
the other limit of a vanishingly small collisional frequency, the
Alfvén waves propagate with an Alfvén speed of the charged
fluid only, while the perturbation in neutral fluid is very small. The
acoustic waves in these limits propagate with the sound speed
corresponding to either the charges or the neutrals, while the
perturbation in the other fluid component is negligible. Otherwise, when
the collision frequency is similar to the real part of the wave
frequency, the interaction between charges and neutrals through
momentum-transfer collisions cause alterations of the waves frequencies
and damping of the wave amplitudes.
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