Pressure anisotropy can strongly influence the dynamics of weakly collisional, high-beta plasmas, but its effects are missed by standard magnetohydrodynamics (MHD). Small changes to magnetic-field strength generate large pressure-anisotropy forces, heating plasma, driving instabilities and rearranging flows, even on scales far above particles’ gyroscales where kinetic traditionally considered m...

The reconnection of magnetic field lines is one of the fundamental processes that lead to the eruptive release of stored magnetic energy in plasmas. A large number of observations and experiments, e.g., solar flares, geomagnetic substorms, the sawtooth instability in fusion experiments, and laboratory reconnection experiments, support this hypothesis. Magnetic reconnection is important for the ...

We review the basic approximations underlying magnetohydrodynamic (MHD) theory, with special emphasis on the closure approximations, i.e. the approximations used in any fluid approach to close the hierarchy of moment equations. We then present the main closure models that have been constructed for collisionless plasmas in the large-scale regime, and we describe our own mixed MHD-kinetic model, ...

This paper aims to study the flow of an incompressible, isothermal Eyring-Powell fluid in a helical screw rheometer. The complicated geometry of the helical screw rheometer is simplified by "unwrapping or flattening" the channel, lands, and the outside rotating barrel, assuming the width of the channel is larger as compared to the depth. The developed second order nonlinear differential equatio...

In this paper, the flow of hydromagnetic non-Newtonian fluid under couple stresses through a porous channel is investigated using the Eyring– Powell model. The fluid is driven by an axial constant pressure gradient. Approximate solutions of the nonlinear dimensionless equations governing the fluid flow are obtained using a new modification of Adomian decomposition method (ADM). The effects of t...

We examine the dynamics of turbulent reconnection in 2D and 3D reduced MHD by calculating the effective dissipation due to coupling between small–scale fluctuations and large–scale magnetic fields. Sweet–Parker type balance relations are then used to calculate the global reconnection rate. Two approaches are employed — quasi–linear closure and an eddy-damped fluid model. Results indicate that d...

The NIMROD and M3D / M3D-C codes now each have both a resistive MHD and a two-fluid (2F) capability including gyroviscosity and Hall terms. We describe: (1) a nonlinear 3D verification test in the resistive MHD regime in which the two codes are in detailed agreement , (2) new studies that illuminate the effect of two-fluid physics on spontaneous rotation in tokamaks, (3) studies of nonlinear re...

Magnetohydrodynamics (MHD) is a model of plasma physics that treats the plasma as a charged fluid. As a result, the set of partial differential equations that describe this model are a time-dependent, nonlinear system of equations. Thus, the equations can be difficult to solve and efficient numerical algorithms are needed. This work shows the use of such an efficient algorithm on the incompress...

The fundamental problem of blood flow in a channel with stenosis under the influence of a steady uniform magnetic field is studied. The mathematical model used for the formulation of the problem is consistent with the principles of Magnetohydrodynamics (MHD). Blood is considered as a homogeneous Newtonian fluid and is treated as an electrically conducting magnetic fluid. The finite volume (FV) ...