Properties of mass-loading shocks: 1. Hydrodynamic considerations

Zank, Gary P.; Oughton, Sean

Properties of mass-loading shocks: 1. Hydrodynamic considerations

dc.contributor.author	Zank, Gary P.
dc.contributor.author	Oughton, Sean
dc.date.accessioned	2014-04-04T02:03:03Z
dc.date.available	2014-04-04T02:03:03Z
dc.date.copyright	1991
dc.date.issued	1991
dc.description.abstract	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, we 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. We 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 u0 must satisfy u0 > ucrit > cs, where cs 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. We suggest the possibility that such structures may describe the inbound Halley bow shock (Coates et al., 1987a). 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.	en_NZ
dc.format.mimetype	application/pdf
dc.identifier.citation	Zank, G. P., & Oughton, S. (1991). Properties of mass-loading shocks: 1. Hydrodynamic considerations. Journal of Geophysical Research, 96(A6), 9439-9453.	en_NZ
dc.identifier.doi	10.1029/91ja00616	en_NZ
dc.identifier.uri	https://hdl.handle.net/10289/8625
dc.language.iso	en	en_NZ
dc.relation.ispartof	J. Geophys. Res.
dc.subject	mass-loading shocks	en_NZ
dc.title	Properties of mass-loading shocks: 1. Hydrodynamic considerations	en_NZ
dc.type	Journal Article	en_NZ