High-order methods for simulations of shocked reactive energetic materials at all scales

Energetic materials (EM), e.g., explosives and propellants, play a pivotal role in various industrial and military applications. Understanding the macro-scale response of EM formulations to shock loading, including the shock-to-detonation transition, is crucial for safety and performance optimization. Closure models for macro-scale sensitivity predictions are developed at the meso-scale, i.e., at the scale of the microstructure, where shock interactions with defects and interfaces are crucial. Therefore, accurate meso-scale simulations are critical to understanding the underlying physics and chemistry of EMs under shock loading and for accurately predicting their sensitivity. Most hydrocodes employed in sensitivity prediction of EMs are typically limited to second-order accuracy at best and require highly resolved simulations to achieve grid-independent solutions. Here, we employ a 5th-order accurate scheme for meso-scale and macro-scale computations. The levelset method is used for sharp interface treatment and a Riemann solver is applied to resolve the interfaces with high accuracy. Shock load analysis of meso-scale pore collapse and pressed HMX microstructures, and macro-scale simulations of flyer impact and confinement effects are used to assess the performance of this high-order numerical method. We show that high-order techniques significantly enhance the accuracy of mesoscale and macroscale simulations and offers outstanding resolution of the interfacial and localization dynamics. Results from high-order simulations are shown to markedly differ from conventional low-order predictions at all scales. These findings are important for the modeling community to take note of in assessing the validity of predictive calculations of the shock dynamics of EMs.