ABSTRACT
At a triple point, which actually is a line, three shocks intersect: an incident (I) shock, a reflected (R) shock, and a Mach stem (M) . At the intersection, a slipstream (SS) is generated. Triple points are ubiquitous in steady and unsteady supersonic flows that contain a shock wave system. Typical flows include over- and under-expanded jets from a supersonic nozzle, shock-shock interference, and steady and unsteady Mach reflection phenomena. Triple points are often discussed for shock wave reflection phenomena, for example, see Courant and Friedrichs (1948), Kalghatgi and Hunt (1975), Hornung (1986), Ben-Dor (1987), Azevedo and Liu (1993), Henderson and Menikoff (1998), Ivanov et al. (1998), Ben-Dor (2007), Mouton and Hornung (2007), and Uskov and Mostovykh (2010). Here, the emphasis is on a unique and comprehensive presentation of the structure and morphology of triple points. By this, we mean the angular orientation of the three shocks and the slipstream, the multiplicity of solutions that satisfy the second law, the strength of the waves, and the relationship between solutions. For example, the reflected shock, R, can have an inverted (i.e, upstream pointing) orientation to one where its orientation is clockwise from the freestream velocity, V → 1 $ \vec{V}_{1} $ https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9781315148076/3e1d211f-7689-4668-814b-399178753123/content/inline-math8_1.tif"/> . While the incident shock is always a weak solution shock, the reflected and Mach stem shocks may be weak or strong. Solution overlap and split solutions are also discussed. Special consideration is provided when the reflected shock or Mach stem is a normal shock.
