Bulletin of the American Physical Society
21st Biennial Conference of the APS Topical Group on Shock Compression of Condensed Matter
Volume 64, Number 8
Sunday–Friday, June 16–21, 2019; Portland, Oregon
Session J5: BIEP: Fragmentation II |
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Chair: Cameron Stewart, Indian Head Room: Broadway I/II |
Tuesday, June 18, 2019 11:00AM - 11:15AM |
J5.00001: Investigation of the Effects of Confinement on Particle Jet Formation in Cylindrical Explosive Dispersal of Particles Bertrand Rollin, Frederick Ouellet, Rahul Koneru, Joshua Garno The explosive dispersal of a layer of solid particles often gives rise to the formation of aerodynamically stable jet-like particle structures. All mechanisms contributing to the formation and selection of these late-time-appearing particle structures have yet to be identified, leading to a wide range of experimental and numerical investigations from several research groups. Generally studied in a spherical geometry, these energetic particle dispersals have recently been experimentally redesigned to occur in a cylindrical geometry, in an attempt at reducing the complexity of the problem. This numerical study focuses on the impact of introducing obstacles at both end of a bed of particles to confine the expansion of the explosive gases and particles into a pseudo-2D cylindrical geometry. Specifically, we present Eulerian-Lagrangian simulations of the sequence of events following the ignition of a PETN chord running through a bed of glass particles sandwiched between two beds of much denser iron powder. Analysis of the interplay between particles at the interface and their effects on the developing particle jets will be discussed. [Preview Abstract] |
Tuesday, June 18, 2019 11:15AM - 11:30AM |
J5.00002: Performance of Erosion and Cohesive Methods in Predicting Fragmentation of Metallic Composites S. K. Dwivedi, A. A. Reinert, D. Stamatis, H. Arbelo-Lopez Modeling fragmentation with size and momenta of fragments in reasonable agreement with experimental data is one of the key requirements for simulating the performance of fragmenting metallic composites (FMC). The present work models fragmentation by erosion and cohesive methods available in LS-DYNA. The shock response of FMC, witness plate during the primary impact- penetration, and anvil material for the secondary impact are described by the Johnson-Cook strength model for deviatoric and Mie-Gruneisen equation-of-state for volumetric responses. The fragmentation by erosion method uses effective plastic strain as well as maximum principal stress criteria for eroding FMC elements. The cohesive method uses irreversible mixed mode cohesive constitutive model along grain boundaries where uniform grain size is the assumed minimum fragment size. Results are presented comparing the fragment size, size distribution, and momenta post primary impact-penetration and secondary impact. The results being obtained in this ongoing work show that the cohesive method, though computationally intensive, is more suitable to model fragmentation due to the conservation of mass, momentum and energy. [Preview Abstract] |
Tuesday, June 18, 2019 11:30AM - 11:45AM |
J5.00003: Investigating the Detonation and Resulting Flow in an Explosive Multiphase Experiment with Uncertainty Quantification Joshua Garno, Frederick Ouellet, Rahul Koneru, Thomas Jackson, S. Balachandar, Bertrand Rollin Up to now, the area of research in compressible multiphase flows has been void of a rigorous investigation into the validity of the compressible Maxey-Riley-Gatignol particle force equation when a high energy, post-detonation flow is imposed on the particle. Laboratory shock-tube experiments and simulations have shown that the model is able to capture the force experienced by the particle due to a passing shockwave and compressed flow, while the present work aims to assess the predictive capability of the model in the context of a single particle subjected to an oncoming detonation wave. Modeling of the gas phase receives primary focus as its evolution in the experiment must be well captured by the simulation in order to allow a justified appraisal of the particle force model. Detonation simulations employ a reactive burn model and explosive products are modeled using the JWL equation of state. High-quality experimental data permits a detailed comparison of defining gas flow features and particle trajectories between experiments and simulations. Several uncertainties, both experimental and model-related, are considered in the finite-volume Euler-Lagrange simulations. [Preview Abstract] |
Tuesday, June 18, 2019 11:45AM - 12:00PM |
J5.00004: Blast Driven Multiphase Instability from the Energetic Dispersal of a Perturbed Particle Bed Frederick Ouellet, Rahul Babu Koneru, Joshua Garno, S. Balachandar, Bertrand Rollin The evolution of a particle cloud following its interaction with a blast wave and contact interface resulting from the detonation of an explosive material is an extremely challenging problem for both numerical simulations and physical experiments. Experimentally, it is difficult to accurately characterize the initial states of both the explosive and a surrounding particle bed. Limitations also exist in the available diagnostic tools and measurable data which can be extracted from experiments. This allows numerical simulations to be a cheaper alternative to analyze mechanisms which govern the interactions between the expanding particle cloud and the highly compressible, post-detonation fluid flow. This work uses multiphase, compressible flow simulations in an Eulerian-Lagrangian frame to analyze the effects of perturbing a uniformly distributed particle bed surrounding an explosive charge. The analysis focuses on the multiphase instabilities and late-time behavior displayed by the particle cloud as it disperses and discusses the underlying physical phenomena associated with the instability. Increasingly complex perturbations are used to unravel the effects of the initial particle distribution and its persistence in the late time particle cloud and the background fluid flow. Inspired by similar two-fluid interfacial instabilities, this study relates to other, previous work in the emerging field of shock-driven multiphase instabilities but at more extreme conditions and at higher, but still moderate, initial particle loadings. [Preview Abstract] |
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