Numerical study on the detonation re-initiation and transverse wave formation in bifurcated hydrogen–oxygen channels

This work presents numerical investigations on the re-initiation dynamics of H2–O2–Ar detonations within bifurcated channels using an OpenFOAM based compressible solver Density-based compressible reactive Foam, focusing on re-initiation mechanisms and transverse wave (TW) formation characteristics. The results show that under high initial pressure p0 = 20 kPa, the decoupled leading shock preheats and compresses unreacted mixtures sufficiently to reduce the ignition delay, enabling TWs to transition into self-sustaining transverse detonation (TD), which re-ignite the decoupled region. In contrast, under low initial pressure p0 = 6.9 kPa, reduced post-shock temperature and pressure conditions result in prolonged ignition delays. Transverse waves fail to form TD, causing progressive detonation decoupling and extinction. Furthermore, for wall reflections induced re-initiation, the re-initiation mechanisms differ under high and low pressures. At 20 kPa, re-initiation is primarily driven by TW interactions, while at 6.9 kPa, it relies on the combined effects of TW interactions and wall hot jets. Three distinct modes of TW formation were identified: (I) emanating from TD fronts and the original detonation, (II) evolving from contact interface instability, and (III) arising from wavefront instability induced by flow expansion. These TW reinforce detonation sustainability through collision-induced hotspots.