New sub-types and transition mechanisms within the canonical six shock interference patterns

Six types of shock wave interference resulting from the impingement of an incident shock on a bow shock are revisited by examining the sub-types that arise between the canonical types. Several new sub-types are predicted based on the theories of weak shock reflection and double-wedge shock interference, and verified via numerical simulations. Two additional types, Type IIw and Type IIs, are identified between Type II and Type III, whereas a Type Vw emerges between Type IV and Type V. These types originate from the transformation of the Mach reflection at the triple point, which evolves through weak shock reflections (von Neumann reflection, Vasilev reflection, Guderley reflection) before disappearing. The transition from Type III to Type IV is further shown to mirror sequences of double-wedge shock interference. Two additional types (Type IIIb and Type IVt) are found. Meanwhile, it is found that under large incoming flow Mach number ( $M_0$ = 5), Types III, IV and their sub-types dominate, whereas Type II is absent; under small incoming flow Mach number ( $M_0$ = 2.5), Types III and IV vanish and a modified Type Va emerges. This study adds seven new sub-types to the existing six types of shock interference. These work extend the classical six types of shock interferences into six-plus shock interference, a picture that shed new insight into shock interference.