Impulse formulations of Hall magnetohydrodynamic (MHD) equations are developed. The Lagrange invariance of a generalized magnetic helicity is established for Hall MHD. The physical implications of this Lagrange invariant are discussed. The discussion is then extended to compressible Hall MHD. Compressibility effects are show not to affect, as to be expected, the physical implications of the gen...

Background Cardiac gating in ultra high field (UHF) MRI is a challenging task due to the magnetohydrodynamic (MHD) effect [1]. The MHD effect is particularly severe at such field strengths and severely distorts the electrocardiogram (ECG). State-of-the-art ECG based gating methods which use the vectorcardiogram (VCG) [2] are thus prone to errors [1]. This work presents an approach which separat...

We present a study of the multiscaling of time-dependent velocity and magnetic-field structure functions in homogeneous, isotropic magnetohydrodynamic (MHD) turbulence in three dimensions. We generalize the formalism that has been developed for analogous studies of time-dependent structure functions in fluid turbulence to MHD. By carrying out detailed numerical studies of such time-dependent st...

It is known that symmetries inherent in the statistical theory of ideal (i.e., nondissipative) magnetohydrodynamic (MHD) turbulence are broken dynamically to produce coherent structure. Previous numerical investigations are extended to study decaying MHD turbulence. Here, we find that coherent structure also arises and persists in the presence of dissipation. Thus, the magnetic dynamo may be du...

the meshless local radial point interpolation (mlrpi) method is applied to examine the magnetohydrodynamic (mhd) ow of third grade uid in a porous medium. the uid saturates the porous space between the two boundaries. several limiting cases of fundamental ows can be obtained as the special cases of present analysis. the variations of pertinent parameters are addressed.

Informed by insights from quantum chaos theory, three approaches for estimating finite-Larmor-radius (FLR) stabilization of ideal magnetohydrodynamic (MHD) instabilities are discussed: phase space criteria based on the Weyl formula, “pseudo-FLR” modifications of MHD to suppress large perpendicular wavenumbers, and inclusion of drift corrections to the dispersion relation. PACS numbers: 52.35.Bj...

Magnetohydrodynamic (MHD) equilibrium states with imposed axisymmetric boundary are computed in which a spontaneous bifurcation develops to produce an internal three-dimensional (3D) configuration with a helical structure in addition to the standard axisymmetric system. Equilibrium states with similar MHD energy levels are shown to develop very different geometric structures. The helical equili...

We review the main properties of shell models for magnetohydrodynamic (MHD) turbulence. After a brief account on shell models with nearest neighbour interactions, the paper focuses on the most recent results concerning dynamical properties and intermittency of a model which is a generalization to MHD of the Gledzer-Yamada-Okhitani (GOY) model for hydrodynamic. Applications to astrophysical prob...

We present a boundary control law that stabilizes the Hartman profile for low magnetic Reynolds numbers in an infinite magnetohydrodynamic (MHD) channel flow. The proposed control law achieves stability in the L2 norm of the linearized MHD equations, guaranteeing local stability for the fully nonlinear system. © 2008 Elsevier B.V. All rights reserved.

The evolutionary conditions for the dissipative continuous magnetohydrodynamic (MHD) shocks are studied. We modify Hada’s approach in the stability analysis of the MHD shock waves. The matching conditions between perturbed shock structure and asymptotic wave modes shows that all types of the MHD shocks, including the intermediate shocks, are evolutionary and perturbed solutions are uniquely def...