Three-dimensional numerical experiments on granulation-generated, two-fluid waves and flows in a solar magnetic carpet

Context. These studies were carried out in the context of solar-chromosphere heating and solar-wind generation. Aims. We aim to explore granulation-generated, two-fluid waves and flows in the solar atmosphere permeated by a solar magnetic carpet. Methods. Three-dimensional (3D) numerical experiments were performed with the use of the JOANNA code, to solve two-fluid equations for ions+electrons and neutrals treated as two separate interacting fluids. We assumed that the plasma is hydrogen and initially described by a hydrostatic state supplemented by the Saha equation. Two model cases were considered: (a) two-fluid equations with ionisation, recombination and radiation switched on; and (b) ideal two-fluid equations. Results. We find that the granulation-generated perturbations in a two-fluid regime and a partially ionised solar chromosphere result in the self-consistent evolution of waves, flows, and the ionisation ratio in the chromosphere and the low corona. In particular, as a result of radiative cooling and recombination as well as jets, which inject partially ionised plasma, the number of neutrals increases in the low corona, and the Fourier spectrum of the excited waves shows some level of convergence to the observational data. Compared to previous findings, ionisation, recombination and radiation result in a larger movement upwards of the transition region, whereas in the idealised case the transition region essentially does not experience its vertical shift by the developed granulation. Conclusions. We infer that 3D effects and the ionisation and recombination operating simultaneously with radiation play a role in evolution of the solar atmosphere, affecting, among a diversity of phenomena, granulation-excited waves, flows, jets, and ionisation levels.