Explosive Hot Spots: Self-Similarity and the Importance of 3D Effects

Shock-induced collapse of voids with diameters in the 100-1000 nm range is thought to govern explosive initiation, but details of the hot spot formation process at this scale remain elusive to "full-physics" treatments based in all-atom molecular dynamics (MD). Using large-scale quasi-2D MD simulations, we predict the initial characteristics of hot spots formed in a model crystalline molecular explosive on multi-micron computational domains. Comparing a range of pore diameters and shock loading orientations shows a high degree of consistency in the of hot spots formed at a given shock strength. Statistical tests are developed that reveal rapid convergence and self-similarity in the predicted hot spot temperature fields with increasing pore diameter for a given orientation and shock strength. Assessments of quasi-2D and full 3D MD simulations of hot spot formation give direct evidence that widely adopted 2D void geometries significantly underestimate the peak temperature under shock initiation conditions. 

 

This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. Approved for unlimited release, LLNL-ABS-843928.