Resolution of an arbitrary discontinuity in magnetohydrodynamics

Гогосов, В.В.

doi:10.1016/0021-8928(61)90104-6

Cited by 37 publications

(12 citation statements)

References 2 publications

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“…When two plasma streams collide, a tangential discontinuity (here the HP) should form that separates the SW and LISM plasmas. This discontinuity can be interpreted as a constituent component of the solution to an MHD Riemann problem [16]. Other MHD discontinuities (fast and slow shocks, contact and rotational (Alfvén) discontinuities, slow-and fast-mode rarefaction waves) may or may not form on the LISM and SW sides of the HP, but the presence of a tangential discontinuity is obligatory.…”

Section: Constraints On the Model Boundary Conditions From Observationsmentioning

confidence: 99%

Heliosheath Processes and the Structure of the Heliopause: Modeling Energetic Particles, Cosmic Rays, and Magnetic Fields

et al. 2017

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Publication resulting from an International ISSI Team of the same name. Submitted to Space Science ReviewsInternational audienceThis paper summarizes the results obtained by the team "Heliosheath Processes and the Structure of the Heliopause: Modeling Energetic Particles, Cosmic Rays, and Magnetic Fields" supported by the International Space Science Institute in Bern, Switzerland. We focus on the physical processes occurring in the outer heliosphere, especially at its boundary called the heliopause (HP), and in the LISM. The importance of magnetic field, charge exchange between atoms and ions, and solar cycle on the heliopause topology and observed heliocentric distances to different heliospheric discontinuities are discussed. It is shown that time-dependent boundary conditions are necessary to describe the heliospheric asymmetries detected by the Voyager spacecraft. We also discuss the structure of the HP, especially due to its instability and magnetic reconnection. It is demonstrated that the Rayleigh-Taylor instability of the nose of the HP creates consecutive layers of the interstellar and heliospheric plasma which are magnetically connected to different sources. This may be a possible explanation of abrupt changes in the galactic and anomalous cosmic ray fluxes observed by Voyager 1 when it was crossing the HP structure for a period of about one month in the summer of 2012. This paper also discusses the plausibility of fitting simulation results to a number of observational data sets obtained by in situ and remote measurements. The distribution of magnetic field in the vicinity of the HP is discussed in the context of Voyager measurements. We discuss the transport of energetic particles in the inner and outer heliosheath, concentrating on the anisotropic spatial diffusion diffusion tensor and the pitch-angle dependence of perpendicular diffusion and demonstrate that the latter can explain the observed pitch-angle anisotropies of both the anomalous and galactic cosmic rays in the outer heliosheath

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Section: Constraints On the Model Boundary Conditions From Observationsmentioning

confidence: 99%

Heliosheath Processes and the Structure of the Heliopause: Modeling Energetic Particles, Cosmic Rays, and Magnetic Fields

et al. 2017

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“…The purpose of this paper is to study the generation of anomalous flows by the interaction between the curved BS and an interplanetary TD or RD. According to the general Riemann problem, the interaction between a fast shock and an MHD discontinuity or shock may lead to the generation of up to seven MHD discontinuities and shock waves [e.g., Gogosov, 1961;Jeffrey and Taniuti, 1964;Neubauer, 1976;Wu et at., 1993; Yan and Lee, 1994Lee, , 1996oein et al, 1996a]. The interaction of the bow shock with interplanetary discontinuities has been studied by gasdynamic theory [Shen and Dryer, 1972;Dryer, 1973], MHD theories for perpendicular shocks [e.g., Volk and Auer, 1974], and MHD simulations [Y an and Lee, 1996].…”

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Generation of anomalous flows near the bow shock by its interaction with interplanetary discontinuities

Lin¹

1997

J. Geophys. Res.

111

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Abstract. Two-dimensional hybrid simulations using a curvilinear coordinate system are carried out to study the interaction of the Earth's bow shock (BS) with an interplanetary directional discontinuity. In particular, plasma flow patterns are examined. In the interaction of the bow shock with an interplanetary tangential discontinuity (TD), a bulge of magnetic field and plasma may be present near the intersection between the fronts of the BS and the TD. The bulge expands to the upstream and is embedded in the solar wind. High magnetic field and ion density are present in the boundary regions of the bulge, and the temperature in the bulge is significantly higher than that in the ambient solar wind. A core of low density and sometimes low field is present inside the bulge. The flow speed changes from supersonic in the solar wind to subsonic throughout the bulge. A strong sunward deflection in flow velocity is present both in the bulge and in the magnetosheath In the interaction of the BS with an interplanetary rotational discontinuity (RD), the flow may be deflected sunward by the magnetic tension force associated with the resulting rotational discontinuities and slow shocks in the magnetosheath. It is suggested that the observed anomalous flow events upstream of the bow shock may be due to the BS/TD interaction, and both BS/RD and BS/TD interactions may generate strong sunward flow deflections in the magnetosheath.

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“…This part of the analysis corresponds to the Riemann problem mentioned previously. In general the Riemann problem is difficult to solve [e.g., Gogosov, 1961], but in our case this is not so [Hcyn ½t al., 1986[Hcyn ½t al., , 1988. This is because only tangential components are involved (perpendicular components appear only in higher orders), pressure constancy implies that fast waves do not appear in this problem, and we are confining the analysis to the incompressible limit.…”

Section: Formulation Of the Problemmentioning

confidence: 99%

Time‐dependent localized reconnection of skewed magnetic fields

Semenov¹,

Kubyshkin²,

Lebedeva³

et al. 1992

J. Geophys. Res.

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We describe and analyze a model for time-varying, localized reconnection in a current sheet with skewed magnetic field orientations on opposite sides. As in Petschek's description, disruption is initiated in a localized part of the current sheet known as the diffusion region, and the disturbances are subsequently propagated into the system at large through magnetohydrodynamlc (MHD) Waves. The MHD waves therefore play the do•ninant role in energy conversion, and collectively they form an outflow for plasma streaming toward the current sheet and a field reversal region joining magnetic field lines from opposite sides. We restrict the analysis to an incompressible plasma, in which case the Affv•n wave and the slow shock merge to form shocks bounding the field reversal or outflow region, and to the case of weak reconnection, which implies that the reconnection electric field is much smaller than the product of the characteristic values of the external field strength and Affv•n speed. It is then possible to perform a perturbation analysis of the MHD equations wlfich govern the plasma and field behavior. The analysis can be formulated as a •nixture of three well-known problems. The problem of determining the appropriate combination of MHD waves corresponds to the Riemann problem, Which also specifies the tangential field and flow components in the field reversal region. These results, it is important to note, are not sensitive to variations in the reco•mection rate. Reconnection also acts as a source of surface waves, and their analysis deternxines the behavior of the perpendicular field and flow components and the shape of the shocks. Lastly, the field reversal region can be considered as a thin boundary layer in our treatment, and the external disturbances can therefore be solved in a way similar to the flow around a thin aerofoil. The model presented here can be applied to the Earth's magnetopause, where recom•ection is considered to be the dominant process coupling the solar wind and the magnetosphere. In particular, the results can be used to interpret different manifestations of ß recotmection such as accelerated i•lasma flows along the magnetopause and flux transfer e•ents. 1. INTRODUCTION Magnetic field line reconnection is a universal energy con? version process in space plasmas [e.g., Vasyliunas, 1975; Hones, 1984; Pudovkin and Seinenov, 1985; Priest, 1985]. It is usually described in terms of magnetic field lines. In this case we can visualize reconnection as a process which "cuts"magnetic field lines and subsequently "connects"the different ends to field lines of different topological origin. An alternative description is in terms of electric currents [Seinenov et al., 1983; Pudovkin and Seinenov, 1985; Biernat et al., 1987]. In this description, reconnection is a process which changes and reorganizes the geometry of a current system. These two descriptions are fully compatible with each other; and in particular the Alfv6n wave, which acts as the carrier of current in a plasma, provides a linking concept. D...

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Resolution of an arbitrary discontinuity in magnetohydrodynamics

Cited by 37 publications

References 2 publications

Heliosheath Processes and the Structure of the Heliopause: Modeling Energetic Particles, Cosmic Rays, and Magnetic Fields

Heliosheath Processes and the Structure of the Heliopause: Modeling Energetic Particles, Cosmic Rays, and Magnetic Fields

Generation of anomalous flows near the bow shock by its interaction with interplanetary discontinuities

Time‐dependent localized reconnection of skewed magnetic fields

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