Detached shock wave

The formation of a shock wave is dependent on the objects that affect the flow field. The conservation of mass, momentum, and energy must be satisfied at any location. This is manifested in the formation of a shock wave at a certain location in the flow field to meet the conservahon equations. In the case of a blunt body in a supersonic flow, the pressure increases in front of the body. The increased pressure generates a detached shock wave to satisfy the conservation equations in the flow field to match the conserved properties between the inflow and outflow in front of the body. The velocity then becomes a subsonic flow behind the detached shock wave. However, the shock wave distant from the blunt body is less affected and the detached shock wave becomes an oblique shock wave. Thus, the shock wave appears to be curved in shape, and is termed a bow shock wave, as illustrated in Fig. C-1. 

Fig. C-2(a) shows an attached shock wave on the tip of a wedge. This is a weak shock wave formed when the associated pressure difference is small. On the other hand, as shown in Fig. C-2(b), a detached shock wave is formed when the pressure difference becomes large. An attached shock wave becomes a detached shock wave when the wedge angle becomes large.

Figure C-2. Attached shock wave (a) and detached shock wave (b).

Although a shock wave may be attached to a projectile at its tip (Fig 3), detachment may occur at slower, though still supersonic, speeds. Or. the other hand, a shock wave of a slowly-moving body becomes attached if it accelerates beyond a certain critical speed which varies for different geometrical forms (Ref 50). When the wave... 

Ibid, 28, 1437-41(1957) (Plane shock waves) and Ibid 29, 167-70(1958) (Oblique shock waves) 52) Dunkle s Syllabus (1957-1958). Properties of Shock Waves, which include Supported Shock Waves (pp 50-1) General Properties of Shock Waves (51-2) Detachment of Shock Waves (52-3) Conditions Behind Shock Front (53-6) Variability of Specific Heats (56-7) Relaxation Processes, Ionization, and Chemical Reaction (57-60) and Shock Waves in Solids (60). 

For the case of high temperatures found in the vicinity of hot stars, or in cloud regions under the influence of a shock wave, or in ionized nebulae, several authors have suggested (c.f. Jura, 1975, Dalgamo and McCray 1973) a gas phase formation scheme which could be a significant source for molecular hydrogen, Hj. The associative detachment reaction... 

Models can also be developed which relax the assumption of spherical symmetry (Jura 1983) and indeed which can incorporate shock waves and internal radiation. Such models may give us some information on the evolution of planetary nebulae from the cool, late-type stars. In this regard it is of interest that Olofsson (private communication) has detected a thick CO shell which has detached itself from its central star, S Set. 

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