Properties of mass-loading shocks. 1. Hydrodynamic considerations
- Univ. of Delaware, Newark (USA)
The one-dimensional hydrodynamics of flows subjected to mass loading are considered anew, with particular emphasis placed on determining the properties of mass-loading shocks. This work has been motivated by recent observations of the outbound Halley bow shock (Neubauer et al., 1990), which cannot be understood in terms of simple hydrodynamical or magnetohydrodynamical descriptions. By including mass injection at the shock, the authors have investigated the properties of the Rankine-Hugoniot conditions on the basis of a geometric formulation of the entropy condition. Such a condition, which is more powerful than the usual thermodynamical formulation, serves to determine those solutions to the Rankine-Hugoniot conditions which correspond to a physically realizable downstream state. On this basis a concise theoretical description of hydrodynamic mass-loading shocks is obtained. They show that mass-loading shocks have more in common with combustion shocks than with ordinary nonreacting gas dynamical shocks. It is shown that for decelerated solutions to the Rankine-Hugoniot conditions to exist, the upstream flow speed u{sub 0} > u{sub crit} > c{sub s}, where c{sub s} is the sound speed. Besides the usual supersonic-subsonic transition, mass-loading fronts can also admit a decelerating supersonic-supersonic transition, the structure of which consists of a sharp decrease in the flow velocity preceding a recovery and an increase in the final downstream flow speed. They suggest the possibility that such structures may describe the inbound Halley bow shock. Both parallel and oblique shocks are considered, the primary difference being that oblique shocks are subjected to a shearing stress due to mass loading. It is conjectured that such a shearing may destabilize the shock.
- OSTI ID:
- 5224398
- Journal Information:
- Journal of Geophysical Research; (United States), Vol. 96:A6; ISSN 0148-0227
- Country of Publication:
- United States
- Language:
- English
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GENERAL PHYSICS
HALLEY COMET
SOLAR WIND
INTERACTIONS
HYDRODYNAMICS
MASS TRANSFER
RANKINE-HUGONIOT EQUATIONS
SHEAR
SHOCK WAVES
STABILITY
SUBSONIC FLOW
SUPERSONIC FLOW
COMETS
EQUATIONS
FLUID FLOW
FLUID MECHANICS
MECHANICS
SOLAR ACTIVITY
640107* - Astrophysics & Cosmology- Planetary Phenomena