Parameter regimes for slow, intermediate and fast MHD shocks

Delmont, Peter; Keppens, Rony

doi:10.1017/s0022377810000115

Cited by 15 publications

(20 citation statements)

References 26 publications

(54 reference statements)

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“…The fast-shock solution is obtained from the cubic equation (2.36) by substituting this M 0 . Although the roots have non-trivial structure in general as discussed in Delmont and Keppens (2011), we can easily pick up the correct root that corresponds to a fast shock as described in Appendix A. Note also that (3.3) is applicable to both left and right fast waves, while we omitted plus and minus signs from the variables, M 0 ,ĉ f 0 , ψ f , s and s max , for simplicity.…”

Section: Parameterization Of Regular Wavesmentioning

confidence: 99%

Exact Riemann solver for ideal magnetohydrodynamics that can handle all types of intermediate shocks and switch-on/off waves

Takahashi

Yamada

2013

J. Plasma Phys.

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We have built a code to obtain the exact solutions of Riemann problems in ideal magnetohydrodynamics (MHD) for an arbitrary initial condition. The code can handle not only regular waves but also switch-on/off rarefactions and all types of non-regular shocks: intermediate shocks and switch-on/off shocks. Furthermore, the initial conditions with vanishing normal or transverse magnetic fields can be handled, although the code is partly based on the algorithm proposed by Torrilhon (2002) (Torrilhon, M. 2002 Exact solver and uniqueness condition for Riemann problems of ideal magnetohydrodynamics. Research report 2002-06, Seminar for Applied Mathematics, ETH, Zurich, Switzerland), which cannot deal with all types of non-regular waves nor the initial conditions without normal or transverse magnetic fields. Our solver can find all the solutions for a given Riemann problem, and hence, as demonstrated in this paper, one can investigate the structure of the solution space in detail. Therefore, the solver is a powerful instrument to solve the outstanding problem of existence and uniqueness of solutions of MHD Riemann problems. Moreover, the solver may be applied to numerical MHD schemes like the Godunov scheme in the future.

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Section: Parameterization Of Regular Wavesmentioning

confidence: 99%

Exact Riemann solver for ideal magnetohydrodynamics that can handle all types of intermediate shocks and switch-on/off waves

Takahashi

Yamada

2013

J. Plasma Phys.

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“…There is an extended literature on the theory of radiative hydrodynamical shock waves generally (Pai 1966;Castor 2004;Li et al 2011), as well as in the optically thick medium (Drake 2007), and for the mixed, optically thick-thin case (McClarren et al 2010;Doss et al 2011).…”

Section: Onićmentioning

confidence: 99%

“…Auluck and Tandon (1966) analyzed the radiation effects on the propagation of a plane perpendicular MHD shocks in a plasma, and Verma and Srivastava (1972) discussed magnetoradiative supersonic flow with variable specific heat. The analysis of parameter regimes for slow, intermediate, and fast MHD shocks were done by Delmont and Keppens (2011). The analysis of parameter regimes for slow, intermediate, and fast MHD shocks were done by Delmont and Keppens (2011).…”

Section: Introductionmentioning

confidence: 99%

Distilled shock conditions for ideal magneto-acoustic shock waves in an optically thick medium

Onić¹

2012

J. Plasma Phys.

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The shock waves are important features in the analysis of transonic magnetohydrodynamical (MHD) flows where thermal radiation could also be significant. In this paper the effects of black-body radiation on non-relativistic shock waves in an ideal radiation MHD model for the optically thick case are discussed. Distilled shock conditions were derived and discussed for the case of a fixed ratio of specific heats of an ideal gas (γ) and ratio of gas to total pressure (b). The special case, when jumps in γ and/or b are allowed, was also considered.

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“…Mangetohydrodynamic (MHD) systems are capable of supporting numerous types of shock transitions due to the three characteristic speeds (slow, Alfvén, fast) (e.g., Delmont & Keppens 2011). Slow-mode shocks feature a transition from superslow to subslow and are of particular importance for magnetic reconnection events (Petschek 1964;Innocenti et al 2015;Shibayama et al 2015).…”

Section: Introductionmentioning

confidence: 99%

Mode conversion of two-fluid shocks in a partially-ionised, isothermal, stratified atmosphere

Snow

Hillier

2020

A&A

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Context. The plasma of the lower solar atmosphere consists of mostly neutral particles, whereas the upper solar atmosphere is mostly ionised particles and electrons. A shock that propagates upwards in the solar atmosphere therefore undergoes a transition where the dominant fluid is either neutral or ionised. An upwards propagating shock also passes a point where the sound and Alfvén speed are equal. At this point the energy of the acoustic shock can separated into fast and slow components. How the energy is distributed between the two modes depends on the angle of magnetic field. Aims. The separation of neutral and ionised species in a gravitationally stratified atmosphere is investigated. The role of two-fluid effects on the structure of the shocks post-mode-conversion and the frictional heating is quantified for different levels of collisional coupling. Methods. Two-fluid numerical simulations are performed using the (PIP) code of a wave steepening into a shock in an isothermal, partially-ionised atmosphere. The collisional coefficient is varied to investigate the regimes where the plasma and neutral species are weakly, strongly and finitely coupled. Results. The propagation speeds of the compressional waves hosted by neutral and ionised species vary, therefore velocity drift between the two species is produced as the plasma attempts to propagate faster than the neutrals. This is most extreme for a fast-mode shock. We find that the collisional coefficient drastically changes the features present in the system, specifically the mode conversion height, type of shocks present, and the finite shock widths created by the two-fluid effects. In the finitely-coupled regime fast-mode shock widths can exceed the pressure scale height leading to a new potential observable of two-fluid effects in the lower solar atmosphere.

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Parameter regimes for slow, intermediate and fast MHD shocks

Cited by 15 publications

References 26 publications

Exact Riemann solver for ideal magnetohydrodynamics that can handle all types of intermediate shocks and switch-on/off waves

Exact Riemann solver for ideal magnetohydrodynamics that can handle all types of intermediate shocks and switch-on/off waves

Distilled shock conditions for ideal magneto-acoustic shock waves in an optically thick medium

Mode conversion of two-fluid shocks in a partially-ionised, isothermal, stratified atmosphere

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