A Simple Reactive‐Flow Model for Corner‐Turning in Insensitive High Explosives, Including Failure and Dead Zones. I. The Model.

Abstract

I report on a novel simple reactive-flow model that captures corner-turning behavior, including failure and the creation of dead zones, in insensitive solid heterogeneous high explosives. The model is fast, has a minimum of free parameters, and is physically grounded in the underlying initiation and burn phenomena. The focus of the model is explosives based on triaminotrinitrobenzene (TATB), although the model is quite general. I initially developed the model and integrated it into a branch of a Lawrence Livermore National Laboratory (LLNL) arbitrary Lagrangian-Eulerian (ALE) code concurrently with other modelling efforts of mine, but I subsequently adopted it to study corner-turning behavior in the TATB-based high explosive PBX 9502 when two other available models suggested to me proved inadequate, being either prohibitively computationally expensive or numerically unstable. An early version of the model reproduces corner-turning behavior in two different double-cylinder tests and a mushroomtype corner turning test. The model was informed and influenced by other reactive-flow models applicable to shock initiation or corner-turning, most especially including JWL++ Tarantula 2011 and an in-house piecewise-linear CHEETAH-based model that exhibits corner-turning behavior, but also, to a degree, by Ignition & Growth (I&G), CREST, and the Statistical Hot-Spot Model. The model also shares some similarities to SURF models. In this paper, I describe the model and its theoretical development as I originally conceived it, as well as subsequent improvements.

A simplified burn model for simulating explosive effects and afterburning

“…Other reactant equations of state could be used [27,39]. However, other reactant EOS models require several input parameters that are not characterized for many materials.…”

“…The solid EOS admits negative pressure, which can cause numerical problems in mixed cells where both explosive and gas are present. For example, a solid density of ρ = 0.9999ρ 0 is low enough to produce negative pressures in (27). A common scenario where this can occur is when the leading shock of the detonation breaks out of the explosive charge.…”

“…Thus, RB approaches can be used with any physically reasonable model for the reactant EOS and reaction rate to produce a physically realistic detonation wave. A similar approach has recently been developed [27], but requires several additional input parameters and may not extend easily to multiphase blasts.…”