Space plasma is a collisionless, multi-scale, and highly nonlinear medium. There are numerous types of selfconsistent computer simulations that treat space plasma according to various approximations. The global-scale dynamics are commonly described by magneto-hydrodynamic (MHD), Hall-MHD and multi-fluid models, while electron-scale processes are described by the kinetic model, i.e., the Maxwell...

The cooperation of nonlinearity ~producing collapsed characteristics! and dispersion ~unfolding singularities! underlies a robust mechanism that imparts two distinct scales (L measuring the system size, and d i typically of the order of the ion skin depth! to the double Beltrami states of a two-fluid plasma. It is shown that the conventional single-fluid model @magnetohydrodynamic ~MHD!# seemin...

The interaction of a comet with the solar wind undergoes various stages as the comet’s activity varies along its orbit. For a comet like 67P/Churyumov–Gerasimenko, the target comet of ESA’s Rosetta mission, the various features include the formation of a Mach cone, the bow shock, and close to perihelion even a diamagnetic cavity. There are different approaches to simulate this complex interplay...

New exact solutions for unsteady magnetohydrodynamic MHD flows of an Oldroyd-B fluid have been derived. The Oldroyd-B fluid saturates the porous space. Two different flow cases have been considered. The analytical expressions for velocity and shear stress fields have been obtained by using Laplace transform technique. The corresponding solutions for hydrodynamic OldroydB fluid in a nonporous sp...

We demonstrate a close analogy between a viscoelastic medium and an electrically conducting fluid containing a magnetic field. Specifically, the dynamics of the Oldroyd-B fluid in the limit of large Deborah number corresponds to that of a magnetohydrodynamic (MHD) fluid in the limit of large magnetic Reynolds number. As a definite example of this analogy, we compare the stability properties of ...