Predicting explosions through analyzing hotspot formation in compacted granular materials

Granular compaction plays an important role in many commercial and industrial applications, such as the production of pharmaceutical tablets, diamond synthesis, and energetic materials. The science of reactive powder mixtures is a complex problem and current solutions rely on models to predict thermal localization in critical areas of the material where ignition will occur. However, it is common for these methodologies to disregard the predictive uncertainty of resulting models, and many questions about modeling assumptions are left unanswered.

Bakarji et al. present a new solution using a probabilistic approach to study reaction initiation in granular materials, and show that treating initial porosity as random is sufficient to capture the hotspot formation with a standard continuum model.

They demonstrated the dependence of reaction ignition on initial pore size distribution using a fluctuating initial microstructure. Using Monte Carlo simulations, their results reproduced the high sensitivity of the probability of reaction initiation to heterogeneity of initial porosity found in experiments. Their results also showed that larger pores dissipate more energy than smaller ones, also consistent with experimental observations.

Referencing Occam’s razor, author Daniel Tartakovsky argued that their approach is “the simplest model with the simplest set of answers able to explain the phenomena.”

However, the research presented has not accounted for chemistry. “We hope to build upon this research to incorporate chemistry and machine learning methods.” Tartakovsky said.

Source: “Microstructural heterogeneity drives reaction initiation in granular materials,” by Joseph Bakarji and Daniel M. Tartakovsky, Applied Physics Letters (2019). The article can be accessed at https://doi.org/10.1063/1.5108902 .