GnarlyX: a mesoscale hydrocode for the extreme deformation of crystalline materials in high explosives applications

We present a new hydrocode, GnarlyX, for investigating shock initiation of plastic bonded explosives (PBX) composed of brittle crystals and polymeric binder. GnarlyX provides a crucial pathway for bridging the microscopic and macroscopic physics of initiation with direct numerical simulations (DNS) of the chemical release and transport at the mesoscale. Our understanding of the behavior of PBX is incomplete because of the lack of experimental support at small scales. GnarlyX is a path to address these shortcomings through a first-principles approach linking deflagration at the microscale to detonation propagation at the macroscale. GnarlyX solves the conservative multi-material hydrodynamic equations, closed with condensed phase equation of states and hyperelastic plastic constitutive models. It has a unique Helmholtz free energy formulation that gives thermodynamically consistent temperature calculations that are essential for high-fidelity reaction. GnarlyX uses robust 3D Eulerian, adaptive mesh refinement for simulating extreme deformation. In this talk, we describe our approach to continuum level modeling at the mesoscale and new computational methods necessary for HE mesoscale DNS.