We explore magnetohydrodynamic (MHD) solutions for envelope expansions with core collapse (EECC) with isothermal MHD shocks in a quasi-spherical symmetry and outline potential astrophysical applications of such magnetized shock flows. By including a random magnetic field in a gas medium, we further extend the recent isothermal shock results of Bian & Lou who have unified earlier similarity isot...

We find and investigate via numerical simulations self-sustained two-dimensional turbulence in a magnetohydrodynamic flow with a maximally simple configuration: plane, noninflectional (with a constant shear of velocity), and threaded by a parallel uniform background magnetic field. This flow is spectrally stable, so the turbulence is subcritical by nature and hence it can be energetically suppo...

The combined effects of mass transfer and rotation on unsteady magnetohydrodynamic (MHD) free convection flow in a porous medium past an infinite inclined plate with ramped wall temperature has been investigated. The effects of thermal diffusion and heat absorption are also observed. Exact solution using Laplace transforms technique has been obtained for the velocity, temperature and concentrat...

This paper investigates hybrid kinetic-magnetohydrodynamic (MHD) models, where a hot plasma (governed by a kinetic theory) interacts with a fluid bulk (governed by MHD). Different nonlinear coupling schemes are reviewed, including the pressure-coupling scheme (PCS) used in modern hybrid simulations. This latter scheme suffers from being non-Hamiltonian and is unable to exactly conserve total en...

Magnetic reconnection changes the topology of magnetic field lines to a lower-energy state. This process can liberate stored magnetic field energy and accelerate particles during unsteady, explosive events. This is one of the most important processes in astrophysical, space and laboratory plasmas. The abrupt onset and cessation has been a long-standing puzzle. We show the first three-dimensiona...

The deposition of energy into the solar wind beyond 1 AU is thought to result from the dissipation of low frequency magnetohydrodynamic (MHD) turbulence via kinetic processes at spatial scales comparable to the ion gyroradius. Beyond 1 AU, solar wind turbulence is comprised of both a decaying component generated in the corona and turbulence generated dynamically in situ by processes such as str...

We have argued that magnetohydrodynamic (MHD) turbulence in an accretion disk naturally produces hoop-stresses, and that in a geometrically-thick flow these stresses could both drive and collimate an outflow. We based this argument on an analogy of turbulent MHD fluids to viscoelastic fluids, in which azimuthal shear flow creates hoop-stresses that cause a variety of flow phenomena, including t...

Linear and nonlinear dynamics of various toroidicity induced global Alfvin eigenmodes is investigated by means of an initial value numerical code. The code uses the reduced magnetohydrodynamic (MHD) model expanded to the third order in the inverse aspect ratio parameter E (E = a/R,, with a the minor radius of the plasma column and R, the major radius of the vacuum chamber). Nonlinear saturation...

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...

Recent ideal magnetohydrodynamic (MHD) theory predicts that a perturbation evolving from a linear ballooning instability will continue to grow exponentially at the same linear growth rate globally in the intermediate nonlinear phase. This theoretical prediction is confirmed in direct MHD simulations of nonlinear ballooning instability growth in a tokamak. The Lagrangian compression, which serve...