However, empirical burn rates are only effective for applications in which the hot-spot distribution is similar to that occurring in the experiment used to calibrate the burn model. In other words, currently available burn models have a limited domain of applicability. Simulations do capture qualitatively the evolution leading to a detonation wave but do not accurately predict the ignition threshold. This is an important issue for explosive safety since accident scenarios typically involve weak stimuli and are in a very different regime from the prompt initiation for which explosive systems are designed and burn models are calibrated. In addition, accident scenarios frequently lead to damaged explosives.
Damage is known to greatly increase the sensitivity of an explosive to initiation.
In effect, damage introduces a dditional heterogeneities and exacerbates the effect of hot spots. These are key features of a damaged material. Consequently, a granular explosive is a suitable model, albeit simplified, for a damaged explosive. However, meso-scale simulations can be used as numerical experiments to gain an understanding of the mechanisms that generate hot spots and their subsequent evolution. In meso-scale simulations individual grains are resolved and the time evolution computed based on a continuum mechanics model.