A Blunt Body in a Supersonic Stream

Rusanov, V. V.

doi:10.1146/annurev.fl.08.010176.002113

Cited by 31 publications

(8 citation statements)

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“…This is for a spherical cold front and γ ad = 5/3. that of the cold front (Rusanov 1976), projection effects will generally cause d s to be overestimated and M 1 to be underestimated. Projection effects also make the true shape of the cold front uncertain.…”

Section: Kinematics Of Cold Frontsmentioning

confidence: 99%

The Physics of Cluster Mergers

Sarazin

2002

Merging Processes in Galaxy Clusters

117

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Clusters of galaxies generally form by the gravitational merger of smaller clusters and groups. Major cluster mergers are the most energetic events in the Universe since the Big Bang. Some of the basic physical properties of mergers will be discussed, with an emphasis on simple analytic arguments rather than numerical simulations. Semi-analytic estimates of merger rates are reviewed, and a simple treatment of the kinematics of binary mergers is given. Mergers drive shocks into the intracluster medium, and these shocks heat the gas and should also accelerate nonthermal relativistic particles. X-ray observations of shocks can be used to determine the geometry and kinematics of the merger. Many clusters contain cooling flow cores; the hydrodynamical interactions of these cores with the hotter, less dense gas during mergers are discussed. As a result of particle acceleration in shocks, clusters of galaxies should contain very large populations of relativistic electrons and ions. Electrons with Lorentz factors gamma~300 (energies E = gamma m_e c^2 ~ 150 MeV) are expected to be particularly common. Observations and models for the radio, extreme ultraviolet, hard X-ray, and gamma-ray emission from nonthermal particles accelerated in these mergers are described.Comment: 38 pages with 9 embedded Postscript figures. To appear in Merging Processes in Clusters of Galaxies, edited by L. Feretti, I. M. Gioia, and G. Giovannini (Dordrecht: Kluwer), in press (2001

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Section: Kinematics Of Cold Frontsmentioning

confidence: 99%

The Physics of Cluster Mergers

Sarazin

2002

Merging Processes in Galaxy Clusters

117

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“…The magnetohydrodynamic (MHD) interaction of an ionized flow with a magnetized body moving in the atmosphere at a hypersonic speed was modelled as early as the 1950s, initiated with theoretical approaches (Bush 1958;Lévy 1963;Levy & Petschek 1963;Jarvinen 1965) and afterwards complemented by numerical simulations stimulated by space flight and atmospheric entry problems (signal blackout, wall heating, drag monitoring…). Numerical resolution of the Euler equations for the aerodynamic blunt-body problem at supersonic speeds was developed in the 1960s (Moretti & Abbett 1966;Moretti & Bleich 1967;Rusanov 1976), soon followed by numerical resolution of the MHD equations (Coackley & Porter 1971), and has reached a high level of accuracy.…”

Section: Introductionmentioning

confidence: 99%

Analytic model of a resistive magnetohydrodynamic shock without Hall effect

Berton

2018

J. Fluid Mech.

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An analytic model of a stationary hypersonic magnetohydrodynamic (MHD) shock with an externally applied magnetic field is proposed. Basically, original jump conditions at a plane oblique shock, analogous to the Rankine–Hugoniot formulae, with a moderately resistive air plasma downstream are derived. Viscous, thermal and Hall effects are neglected, but the plasma dissociation behind the shock causing a jump of isentropic exponent is also a major input of the model. Then, a shock-fitting procedure with ambient atmospheric conditions is worked out by the coupling of these MHD jumps with thermodynamic correlations and an electric conductivity model. For an application to atmospheric entry problems, the flow behind an axisymmetric blunt-body shock is modelled with a stream function satisfying these MHD jump conditions as boundary conditions. An important feature put into evidence is a similarity rule involving the hypersonic parameter$M_{1}\cos \unicode[STIX]{x1D712}_{1}$, which shows an aerodynamic correspondence between the upstream Mach number$M_{1}$and the velocity angle$\unicode[STIX]{x1D712}_{1}$. It also emerges that curvature effects become important past$30^{\circ }$and the assumption of a spherical shock also becomes untenable past$50^{\circ }$; therefore, we limit the model of shock thickness used in the MHD fitting to$\unicode[STIX]{x1D712}_{1}<50^{\circ }$.

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“…Of interest is the spike in the pressure distribution close to x=l 0:02. This would appear to be a mild compression or weak shock wave caused by an overexpansion of the flow at the shoulder of the small-radius nose [25], and is barely predicted by the realizable k-". Shock-adaptation of the mesh for the realizable simulations does not extensively change this.…”

Section: Turbulence Modellingmentioning

confidence: 99%

Aerodynamics of a Supersonic Projectile in Proximity to a Solid Surface

Doig¹,

Barber²,

Leonardi³

et al. 2010

AIAA Journal

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Flow around a Mach 2.4 NATO 5.56 mm projectile in close proximity to a ground plane was investigated using computational fluid dynamics for a direct numerical reproduction of live-range experiments. The numerical approach was validated against both the live-range tests and subsequent wind-tunnel experiments. A nonspinning half-model and a full, spinning projectile were examined to clarify the influence of rotation. Multiple ground clearances were tested to obtain clear trends in changes to the aerodynamic coefficients, and the three-dimensional propagation and reflection of the shock waves were considered in detail. The behavior of the flow in the near wake was also studied as ground clearance was reduced. Ground proximity was found to significantly increase the drag force acting on the projectile, as well as generate a force normal to the ground and an increased side force, when ground clearance was less than one diameter. For clearances between approximately 0.4 and 1 diameter, the pitching moment produced was nose-down. For lower clearances, a more distinct nose-up trend was produced. The generated side force was orders of magnitude lower than the normal and drag forces.

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A Blunt Body in a Supersonic Stream

Cited by 31 publications

References 0 publications

The Physics of Cluster Mergers

The Physics of Cluster Mergers

Analytic model of a resistive magnetohydrodynamic shock without Hall effect

Aerodynamics of a Supersonic Projectile in Proximity to a Solid Surface

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