We present a detailed temporal analysis of a set of hydrodynamic and magnetohydrodynamic (MHD) simulations of geometrically-thin (h/r ∼ 0.05) black hole accretion disks. The black hole potential is approximated by the Paczynski-Wiita pseudo-Newtonian potential. In particular, we use our simulations to critically assess two widely discussed models for high-frequency quasi-periodic oscillations, ...

Large CFD problems are often solved using iterative methods. Preconditioning is mandatory to accelerate the convergence of iterative methods. This paper presents new results using several preconditioning techniques. These preconditoners are non-standard in the CFD community. Several numerical tests were carried out for solving three-dimensional incompressible, compressible and magneto-hydrodyna...

Prediction of solar storms has become a very important issue due to the fact that they can affect dramatically the telecommunication and electrical power systems in the earth. As a result, a lot of research is being doing in this direction, space weather forecast. Magneto-Hydrodynamics systems are being studied in order to analyze the space plasma dynamics, and techniques which have been broadl...

This work revisits the star formation rate (SFR) model of Krumholz and McKee, extends it to the case of a magnetized medium, and verifies it with a set of numerical simulations of driven, supersonic, magneto-hydrodynamic (MHD) turbulence, where collapsing cores are captured with accreting sink particles. The main results are: i) a new physical interpretation of the critical density for star for...

Theories for the toroidal momentum confinement in tokamaks have been developed. It is shown that the logarithmic gradient of the toroidal flow is a linear combination of logarithmic gradients of the plasma pressure and the temperature in neoclassical quasilinear theory. The fluctuation-induced toroidal stress consists of a diffusion flux, a convective flux, and a residual flux. The effects of a...

The studies of standard and neoclassical tearing instabilities in experimental tokamak plasmas show that these modes can be a serious problem on the path toward magnetic fusion. A precise understanding of their dynamics therefore is crucial, but requires full toroidal extended magneto-hydrodynamic (MHD) simulations. Solving this problem is difficult, both from the point of view of the extreme p...

The use of Magneto Hydro Dynamics (MHD) to circulate fluids in conduits fabricated with low temperature co-fired ceramic tapes is described. Conduits shaped like toroidal and rectangular loops were fabricated. Electrodes printed on the ceramic substrate along the conduits' walls facilitated transmission of electric currents through the test fluids. When the devices were subjected to a magnetic ...

This research focuses on entropy generation rate per unit volume in magneto-hydrodynamic (MHD) mixed convection boundary layer flow of a viscous fluid over an inclined stretching sheet. Analysis has been performed in the presence of viscous dissipation and non-isothermal boundary conditions. The governing boundary layer equations are transformed into ordinary differential equations by an approp...

In this paper a mathematical analysis of effect of couple stresses on magneto hydrodynamic (MHD) flow past a parallel plate channel of viscous, incompressible and electrically conducting fluid in the presence of porous medium has been studied. An exact solution of the dimensionless governing equations has been obtained by using method of perturbation technique. The effects on velocity, discharg...