Shock Waves Propagating in a Channel with Obstacles

Up today it is not fully understood how many mechanisms are involved in the propagation of a deflagration and in its transition to detonation but it clearly appears both from experimental and numerical analysis that the onset of a detonation is likely to be initiated by the presence of hot spots behind a shock wave. This kind of small regions can occur in various circumstances amongst many other shock turbulence interaction shock boundary layer interaction and shock flame interaction must be mentioned. In all cases quantitative results concerning the occurrence of a sufficiently strong hot spot for the detonation to be initiated are not close in hands. In this study we focus on the more simple configuration of a shock wave propagating in an inert confined mixture air with the eventual aim of determining which are the leading energy transfer mechanisms affecting the formation of hot spots. One of the key point to address is the fact that in the case of a planar shock wave the presence of the confinement causes a scattering of the energy in all possible components and this augments the amount of energy that is dissipated diminishing the strength of the shock iteself. Herein a preliminar attempt is made to measure how the energy scattering is aected by the different size of obstacles and shock strengths. To this aim highly resolved numerical solution of the compressible Navier-Stokes equations have been carried out. This level of simulation is believed to be mandatory if physical dissipative mechanisms have to be accounted for.