Influence of Channel Confinement on Micro-Jetting Dynamics and Cellular Structures in Three-Dimensional Hydrogen Detonations

Micro-jetting and cellular structure in gaseous detonations are strongly influenced by the three-dimensional organization of transverse-wave interactions and by near-wall losses in confined channels. This work investigates these effects using detailed-chemistry simulations of hydrogen-oxygen-argon detonations in wide and thin channel configurations. The wide-channel case is used to examine fully three-dimensional micro-jet morphology, while the thin-channel cases are used to separate the effects of geometric confinement, momentum loss, and combined momentum and thermal loss. The results show that confinement changes the observed micro-jet topology from elongated jet-line structures in the thin channel to vortex-loop and mushroom-shaped structures in the wide channel. Within the thin-channel, momentum loss mainly modifies the near-wall flow characteristics and jet strength, while the addition of thermal loss changes the post-shock profile, increases the effective induction-zone thickness, and produces larger observed cellular sizes. The localized cell-cycle diagnostics further show that, in the no-slip isothermal case, the transverse-wave and micro-jet velocity maxima are reduced near the wall relative to the channel center, while the peak pressure remains comparable and can be slightly larger near the wall because of local compression. These results provide a focused comparison of how confinement and wall boundary conditions modify micro-jetting dynamics and associated detonation cellular structures.