Regular and Mach Reflection of Shock Waves

Hornung, H. G.

doi:10.1146/annurev.fl.18.010186.000341

Cited by 225 publications

(99 citation statements)

References 27 publications

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“…1b). This convergence of the flow on axis generates a conical shock [63] at the longitudinal tip of the cavity (z ∼ 4 mm at 16 ns), which then re-directs the flow again. Since the plane of the conical shock is along the z-axis, the flow is symmetrically refracted along the z-axis and a collimated jet is formed.…”

Section: Electron Density Evolution With 20 T Magnetic Fieldmentioning

confidence: 99%

Detailed characterization of laser-produced astrophysically-relevant jets formed via a poloidal magnetic nozzle

Higginson

Revet

Khiar

et al. 2017

High Energy Density Physics

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This manuscript is distributed under a Creative Commons Attribution-NonCommercial-NoDerivs License (https://creativecommons.org/licenses/by-nc-nd/4.0/), which permits distribution and reproduction for non-commercial purposes, provided the author and source are cited. General rightsCopyright for the publications made accessible via the Queen's University Belfast Research Portal is retained by the author(s) and / or other copyright owners and it is a condition of accessing these publications that users recognise and abide by the legal requirements associated with these rights. AbstractThe collimation of astrophysically-relevant plasma ejecta in the form of narrow jets via a poloidal magnetic field is studied experimentally by irradiating a target situated in a 20 T axial magnetic field with a 40 J, 0.6 ns, 0.7 mm diameter, high-power laser. The dynamics of the plasma shaping by the magnetic field are studied over 70 ns and up to 20 mm from the source by diagnosing the electron density, temperature and optical self-emission. These show that the initial expansion of the plasma is highly magnetized, which leads to the formation of a cavity structure when the kinetic plasma pressure compresses the magnetic field resulting in an oblique shock [A. Ciardi et al., Phys. Rev. Lett. 110, 025002 (2013)]. The resulting poloidal magnetic nozzle generates a standing conical shock that collimates the plasma into a narrow jet [B. Albertazzi et al., Science 346, 325 (2014).]. At distances far from the target, the jet is only marginally magnetized and maintains a high aspect ratio due to its high Mach-number (M ∼ 20) and not due to external magnetic pressure. The formation of the jet is evaluated over a range of laser intensities (10 12 -10 13 W/cm 2 ), target materials and orientations of the magnetic field. Plasma cavity formation is observed in all cases and the viability of long-range jet formation is found to be dependent on the orientation of the magnetic field.

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Section: Electron Density Evolution With 20 T Magnetic Fieldmentioning

confidence: 99%

Detailed characterization of laser-produced astrophysically-relevant jets formed via a poloidal magnetic nozzle

Higginson

Revet

Khiar

et al. 2017

High Energy Density Physics

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“…As discussed above, at θ w = 45 • , a regular reflection is observed, while at θ w = 44 • , the reflection takes the form of a Mach reflection, characterised by a Mach shock travelling nearly perpendicular to the wall. A second triple-shock configuration (triple-point), also with an associated slip line, which becomes unstable due to the Kelvin-Helmholtz instability, can be found along the reflected wave and corresponds to the sub-regime of double Mach reflection [2]. This double Mach reflection has a negative reflection angle (between the triple-point path and reflected wave) [28].…”

Section: Resultsmentioning

confidence: 95%

“…The isentropic exponent γ, the geometry (angle of the wall), and the Mach number of the incident shock M i = D/c 0 uniquely define the problem; the type of reflection is subject to change with any of those variables. Thorough reviews of the shock reflection problem have been provided by Hornung [2] and Ben-Dor [1].…”

Section: Introductionmentioning

confidence: 99%

Non-uniqueness of solutions in asymptotically self-similar shock reflections

Lau-Chapdelaine

Radulescu

2013

Shock Waves

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The present study addresses the self-similar problem of unsteady shock reflection on an inclined wedge. The start-up conditions are studied by modifying the wedge corner and allowing for a finite radius of curvature. It is found that the type of shock reflection observed far from the corner, namely regular or Mach reflection, depends intimately on the start-up condition, as the flow "remembers" how it was started. Substantial differences were found. For example, the type of shock reflection for an incident shock Mach number M = 6.6 and an isentropic exponent γ = 1.2 changes from regular to Mach reflection between 44 • and 45 • when a straight wedge tip is used, while the transition for an initially curved wedge occurs between 57 • and 58 • .

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“…For the reflection of the wedge-generated shock wave in two-dimensional flows, a hypothesis based on one-dimensional treatment of the virtual stream forming downstream of the Mach stem was commonly used [12,18]. This stream is primarily subsonic; the flow in it accelerates to form a virtual throat where the flow velocity becomes sonic; the stream becomes supersonic further downstream.…”

Section: Determining the Mach Disk Positionmentioning

confidence: 99%

Patterns of steady axisymmetric supersonic compression flows with a Mach disk

Gounko

2016

Shock Waves

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Results of a numerical simulation of steady axisymmetric supersonic flows in convergent conical ducts and in overexpanded jets are presented. The characteristic feature of these compression flows is the formation of an initial longitudinally curved shock wave with intensity increasing downstream and toward the flow axis, which is finalized by the generation of a central Mach disk. Computations have demonstrated patterns of an irregular interaction of these shocks followed by the formation of a triple-shock configuration, including a reflected shock and a shear layer with entropy varying across the layer. The formation of triple-shock configurations is analogous to the configurations known for the steady inviscid two-dimensional flows where the irregular reflection of a wedge-generated shock from a wall with Mach stem formation occurs. Either a single triple-shock Mach configuration occurs or a triple-shock configuration corresponding to the von Neumann paradox condition is formed at the considered flow Mach numbers and initial angles of deflection to the axis of the flow behind the longitudinally curved shock wave.

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Regular and Mach Reflection of Shock Waves

Cited by 225 publications

References 27 publications

Detailed characterization of laser-produced astrophysically-relevant jets formed via a poloidal magnetic nozzle

Detailed characterization of laser-produced astrophysically-relevant jets formed via a poloidal magnetic nozzle

Non-uniqueness of solutions in asymptotically self-similar shock reflections

Patterns of steady axisymmetric supersonic compression flows with a Mach disk

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