- Repository of the Academy`s Library

... frequency (ULF) waves in the frequency band from fractions of mHz to a few Hz. Interestingly, despite very different spatial scales, MHD wave processes observed in the solar corona have frequencies in the same band. We describe both theoretical models and analysis of observational ground and satelli ...

... frequency (ULF) waves in the frequency band from fractions of mHz to a few Hz. Interestingly, despite very different spatial scales, MHD wave processes observed in the solar corona have frequencies in the same band. We describe both theoretical models and analysis of observational ground and satelli ...

Gravitational Waves from 3D MHD Core

... inner core of some such cataclysmic events, supplying us for example with valuable information about the angular momentum distribution and the baryonic equation of state, both of which are uncertain. Furthermore, they might even help to constrain theoretically predicted SN mechanisms. However, GW as ...

... inner core of some such cataclysmic events, supplying us for example with valuable information about the angular momentum distribution and the baryonic equation of state, both of which are uncertain. Furthermore, they might even help to constrain theoretically predicted SN mechanisms. However, GW as ...

The Earliest Stages of Star and Planet Formation: Core Collapse

... subtle in magnetized gas. In this case, the rotation can be strongly magnetically braked. Indeed, both analytic arguments and numerical simulations have shown that disk formation is suppressed in the strict ideal magnetohydrodynamic (MHD) limit for the observed level of core magnetization. We review ...

... subtle in magnetized gas. In this case, the rotation can be strongly magnetically braked. Indeed, both analytic arguments and numerical simulations have shown that disk formation is suppressed in the strict ideal magnetohydrodynamic (MHD) limit for the observed level of core magnetization. We review ...

Numerical models of sunspot formation and fine structure

... thermal equilibrium, and the fact that the frequency dependence of opacities can be captured sufﬁciently well in most cases by either grey or multi-band approaches. Many of these approximations were introduced by Nordlund [33] and have been reviewed recently in the study of Nordlund et al. [34], see ...

... thermal equilibrium, and the fact that the frequency dependence of opacities can be captured sufﬁciently well in most cases by either grey or multi-band approaches. Many of these approximations were introduced by Nordlund [33] and have been reviewed recently in the study of Nordlund et al. [34], see ...

THE DENSITY VARIANCE – MACH NUMBER RELATION IN

... Mach 10 resolved a maximum density at 1283 particles similar to that captured on a fixed grid at 5123 grid cells. This is consistent with the results here, where it is necessary to refine the grid to an effective 81923 for the Mach 20 calculations employing 5123 SPH particles. It is also evident tha ...

... Mach 10 resolved a maximum density at 1283 particles similar to that captured on a fixed grid at 5123 grid cells. This is consistent with the results here, where it is necessary to refine the grid to an effective 81923 for the Mach 20 calculations employing 5123 SPH particles. It is also evident tha ...

Numerical modeling of plasma structures and turbulence transport in

... mankind for a long time. It was not until the early 20th century – after establishing quantum mechanics – that it was recognized by Eddington that thermonuclear fusion held the answer, whereas earlier ideas like gravitational contraction, which put the Sun’s lifetime at a few million years only, cou ...

... mankind for a long time. It was not until the early 20th century – after establishing quantum mechanics – that it was recognized by Eddington that thermonuclear fusion held the answer, whereas earlier ideas like gravitational contraction, which put the Sun’s lifetime at a few million years only, cou ...

Thermal conduction effects on the kink instability in coronal loops

... electrons lengthen cooling times considerably. However, they also showed that in the parameter space discussed in this paper, the Spitzer-Härm formalism is a very good approximation even when nonlocal eﬀects are considered. Equations (2) and (4) use a single isotropic pressure, which is most easily ...

... electrons lengthen cooling times considerably. However, they also showed that in the parameter space discussed in this paper, the Spitzer-Härm formalism is a very good approximation even when nonlocal eﬀects are considered. Equations (2) and (4) use a single isotropic pressure, which is most easily ...

Chandra HETGS Multiphase Spectroscopy Of The Young

... the field still manages to divert some material toward the magnetic equator, leading to a noticeable density enhancement. Because the magnetic field energy density falls off significantly faster than the wind kinetic energy density, at large radii the wind always dominates over the field, even for ...

... the field still manages to divert some material toward the magnetic equator, leading to a noticeable density enhancement. Because the magnetic field energy density falls off significantly faster than the wind kinetic energy density, at large radii the wind always dominates over the field, even for ...

Magnetized massive stars as magnetar progenitors

... from the main-sequence phase of their progenitors, and the attempt to link magnetic white dwarfs with their main-sequence progenitors naturally makes the chemically peculiar Ap and Bp stars plausible candidates. Observations of Aurière et al. (2003) have shown that chemically peculiar Ap and Bp sta ...

... from the main-sequence phase of their progenitors, and the attempt to link magnetic white dwarfs with their main-sequence progenitors naturally makes the chemically peculiar Ap and Bp stars plausible candidates. Observations of Aurière et al. (2003) have shown that chemically peculiar Ap and Bp sta ...

Investigation of mass flows in the transition region and corona in a

... changes that are less substantial than expected for the case of the static 1D empirical models (see Fig. 5 of Peter et al. 2006). Thus, it can be assumed that temperature gradients in the 3D model are being properly resolved. However, to synthesize transition region emission lines, the temperatures ...

... changes that are less substantial than expected for the case of the static 1D empirical models (see Fig. 5 of Peter et al. 2006). Thus, it can be assumed that temperature gradients in the 3D model are being properly resolved. However, to synthesize transition region emission lines, the temperatures ...

JET FORMATION FROM MASSIVE YOUNG STARS

... formation starts with similar MHD acceleration processes compared to the low-mass models during the earliest evolutionary stages. However, as soon as the central sources gain significant mass, other processes come into play, for example, the radiation from the central star or more turbulence at the ...

... formation starts with similar MHD acceleration processes compared to the low-mass models during the earliest evolutionary stages. However, as soon as the central sources gain significant mass, other processes come into play, for example, the radiation from the central star or more turbulence at the ...

Observations of ubiquitous compressive waves in the Sun`s

... field is much longer than the plasma flows that generate the visible structuring. Waves may be present in the atmosphere even when the magnetic field is not outlined by an intensity enhancement; however, they are far more difficult to identify directly. These intensity enhancements suggest a greater ...

... field is much longer than the plasma flows that generate the visible structuring. Waves may be present in the atmosphere even when the magnetic field is not outlined by an intensity enhancement; however, they are far more difficult to identify directly. These intensity enhancements suggest a greater ...

talk-tutorial - Helioseismic and Magnetic Imager

... Most active regions exhibit only small amounts of twist, and are consistent with a tube lying initially at the base of the convection zone with no twist. How then do the island δ-spot regions ...

... Most active regions exhibit only small amounts of twist, and are consistent with a tube lying initially at the base of the convection zone with no twist. How then do the island δ-spot regions ...

Spheromaks, solar prominences, and Alfvén instability of current

... using a magnetized plasma gun source designed to impose a finite electrostatic potential difference across the ends of an open flux tube that intercepts the bounding surface. In general, the bounding surface is a flux conserving wall which imposes the condition that the normal magnetic field vanishe ...

... using a magnetized plasma gun source designed to impose a finite electrostatic potential difference across the ends of an open flux tube that intercepts the bounding surface. In general, the bounding surface is a flux conserving wall which imposes the condition that the normal magnetic field vanishe ...

Fluid Instabilities

... (a)When the velocities were sufficiently low, the streak of color extended in a beautiful straight line through the tube. (b)As the velocity was increased by small stages, at some point in the tube, the color band would all at once mix up with the surrounding water, and fill the rest of the tube wit ...

... (a)When the velocities were sufficiently low, the streak of color extended in a beautiful straight line through the tube. (b)As the velocity was increased by small stages, at some point in the tube, the color band would all at once mix up with the surrounding water, and fill the rest of the tube wit ...

Geophysical Turbulence Program

... observational and numerical data and modeling. Invited set of Lectures EEC School on Astrophysical Plasmas, L Vlahos and P Cargill, Ed., Springer-Verlag, 69-131 Carlos Cartes, Miguel D. Bustamante, Annick Pouquet, Marc E. Brachet,Generalized Eulerian-Lagrangian description of Navier-Stokes and resis ...

... observational and numerical data and modeling. Invited set of Lectures EEC School on Astrophysical Plasmas, L Vlahos and P Cargill, Ed., Springer-Verlag, 69-131 Carlos Cartes, Miguel D. Bustamante, Annick Pouquet, Marc E. Brachet,Generalized Eulerian-Lagrangian description of Navier-Stokes and resis ...

David L. Meier, , 84 (2001); DOI: 10.1126/science.291.5501.84

... The flow of a magnetized plasma is most generally described by kinetic theory, general relativity, and Maxwell’s equations for the ...

... The flow of a magnetized plasma is most generally described by kinetic theory, general relativity, and Maxwell’s equations for the ...

Experimental Evidence for a Reduction in Electron Thermal

... advance that has allowed this work is simply the improvement of computer technology. The simulation presented here uses a force-free equilibrium, so the input resistivity profile, taken from experimental data, was fixed in time for the entire simulation. This means that, while the 3D fluctuations in ...

... advance that has allowed this work is simply the improvement of computer technology. The simulation presented here uses a force-free equilibrium, so the input resistivity profile, taken from experimental data, was fixed in time for the entire simulation. This means that, while the 3D fluctuations in ...

CFD SOLUTION of MHD - Journal of applied science in the

... equation. Both methods are solved by scalar transport equations. Solution by magnetic induction uses two or three transport equations (2D or 3D solution). Solution by electric potential uses only one transport equation. MHD module is relatively new and some computing limits and other parts (solidifi ...

... equation. Both methods are solved by scalar transport equations. Solution by magnetic induction uses two or three transport equations (2D or 3D solution). Solution by electric potential uses only one transport equation. MHD module is relatively new and some computing limits and other parts (solidifi ...

Steady Stagnation Point Flow and Heat Transfer Over a Shrinking

... we have investigated a numerical solution on a MHD stagnation-point flow with heat transfer over a shrinking sheet in the presence of magnetic field having interest to the engineering community and to the investigators dealing with the problem in geophysics, astrophysics, electrochemistry and polyme ...

... we have investigated a numerical solution on a MHD stagnation-point flow with heat transfer over a shrinking sheet in the presence of magnetic field having interest to the engineering community and to the investigators dealing with the problem in geophysics, astrophysics, electrochemistry and polyme ...

Energy conservation and Poynting`s theorem

... The Faraday disk is known as an intrinsically high-current low-voltage device,12 and Eq. (5) can help us understand why. An application of Ohm’s law gives I=e ¼ R1 ¼ 2prh=lnðb=aÞ. Consider a disk made of a typical conductor, say aluminum, for which r ¼ 3.8 107 S/m.13 If I were 1 A, then even if b ...

... The Faraday disk is known as an intrinsically high-current low-voltage device,12 and Eq. (5) can help us understand why. An application of Ohm’s law gives I=e ¼ R1 ¼ 2prh=lnðb=aÞ. Consider a disk made of a typical conductor, say aluminum, for which r ¼ 3.8 107 S/m.13 If I were 1 A, then even if b ...

Local conservative regularizations of compressible magnetohydrodynamic and neutral flows

... It is clearly smaller in denser regions and larger in rarified regions. The R-Euler system is readily extended to include conservative body forces F = −ρ∇V by adding V to σ. This extension would be relevant for gravitational systems encountered in astrophysics. A much less trivial extension is to co ...

... It is clearly smaller in denser regions and larger in rarified regions. The R-Euler system is readily extended to include conservative body forces F = −ρ∇V by adding V to σ. This extension would be relevant for gravitational systems encountered in astrophysics. A much less trivial extension is to co ...

Irregular Shock Refraction in Magnetohydrodynamics

... and attempted magnetohydrodynamic power generation or inlet control in scramjets. Such interactions may be modeled in the framework of ideal magnetohydrodynamics (MHD). In MHD, the presence of a magnetic field B greatly alters the regular shock refraction process, as illustrated in figure 2(b): Addi ...

... and attempted magnetohydrodynamic power generation or inlet control in scramjets. Such interactions may be modeled in the framework of ideal magnetohydrodynamics (MHD). In MHD, the presence of a magnetic field B greatly alters the regular shock refraction process, as illustrated in figure 2(b): Addi ...

Magnetic Reconnection Project

... • Why is the magnetic energy during magnetic reconnection released as an explosion? – Since reconnection can be fast why isn’t the magnetic energy released as fast as external drivers can supply it? – Need to explain why magnetic reconnection is not always fast. ...

... • Why is the magnetic energy during magnetic reconnection released as an explosion? – Since reconnection can be fast why isn’t the magnetic energy released as fast as external drivers can supply it? – Need to explain why magnetic reconnection is not always fast. ...

21 Congrès Français de Mécanique ...

... simulate real conditions. The finite difference scheme adopted for the resolution is very similar to that used by R.Peyret [13], A.Ghezal et al [14] and[15], this is a semi implicit scheme of Crank-Nicholson type. We used the Marker And Cell (MAC) for the spatial discretization. The iterative proced ...

... simulate real conditions. The finite difference scheme adopted for the resolution is very similar to that used by R.Peyret [13], A.Ghezal et al [14] and[15], this is a semi implicit scheme of Crank-Nicholson type. We used the Marker And Cell (MAC) for the spatial discretization. The iterative proced ...

# Magnetohydrodynamic generator

A magnetohydrodynamic generator (MHD generator) is a magnetohydrodynamic device that transforms thermal energy and kinetic energy into electricity. MHD generators are different from traditional electric generators in that they operate at high temperatures without moving parts. MHD was developed because the hot exhaust gas of an MHD generator can heat the boilers of a steam power plant, increasing overall efficiency. MHD was developed as a topping cycle to increase the efficiency of electric generation, especially when burning coal or natural gas. MHD dynamos are the complement of MHD propulsors, which have been applied to pump liquid metals and in several experimental ship engines.An MHD generator, like a conventional generator, relies on moving a conductor through a magnetic field to generate electric current. The MHD generator uses hot conductive plasma as the moving conductor. The mechanical dynamo, in contrast, uses the motion of mechanical devices to accomplish this. MHD generators are technically practical for fossil fuels, but have been overtaken by other, less expensive technologies, such as combined cycles in which a gas turbine's or molten carbonate fuel cell's exhaust heats steam to power a steam turbine.Natural MHD dynamos are an active area of research in plasma physics and are of great interest to the geophysics and astrophysics communities, since the magnetic fields of the earth and sun are produced by these natural dynamos.