Observation of deflagration wave in energetic materials using reactive molecular dynamics

Joshi, Kaushik; Chaudhuri, Santanu

doi:10.1016/j.combustflame.2017.05.009

Cited by 22 publications

(14 citation statements)

References 53 publications

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“…Recently, multimillion atom simulations were able to probe the shock to deflagration transition upon collapse of a nanoscale cylindrical pore, , to elucidate the dynamic transition in the crystal structure during chemical reactions at the shock front prior to detonation . Reactive molecular dynamics (MD) simulations have been used extensively to investigate the chemical decomposition and mechanical response of a range of HE materials such as RDX, HMX, PETN, TNT, and NM. ,,− However, despite remarkable progress in atomistic simulations, they are not without limitations. The parametrization of the force fields to describe the tremendously intricate coupling between the mechanics of shock loading and chemical decomposition of HE materials often entails trade-offs in the description of different physical and chemical properties.…”

Section: Introductionmentioning

confidence: 99%

Reactive Molecular Dynamics Simulations to Investigate the Shock Response of Liquid Nitromethane

Islam

Strachan

2019

J. Phys. Chem. C

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We use molecular dynamics (MD) simulations with the ReaxFF reactive force field to investigate the thermomechanical, chemical, and spectroscopic response of nitromethane (NM) to shock loading. We simulate shocks using the Hugoniostat technique and use four different parametrizations of ReaxFF to assess the sensitivity of the results with respect to the force field. The predicted shock states, for both the unreacted and reacted materials, are in good agreement with experiments, and two of the force fields capture the increase in shock velocity due to exothermic reactions in excellent agreement with experiments. The predicted detonation velocities with these two force fields are also in good agreement with experiments, and the differences in predicted values are linked to the differences in the reaction products. Across all force fields, NM decomposes predominantly via bimolecular reactions and the formation of nitrosomethane (CH3NO) is found as a dominant initiation pathway. We elucidate the mechanisms of secondary reactions leading to stable products, whose predicted populations with all four descriptions are in good agreement with experiments. We also calculated the time-resolved spectra from the trajectories during the shock processes to help correlate the underlying reaction mechanisms with spectral features and enable a one-to-one comparison with laser-driven shock experiments. This study demonstrates the potential of reactive molecular dynamics to describe the physics and chemistry of high-energy density materials under shock loading and complement experimental efforts to derive a definite, validated understanding.

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Section: Introductionmentioning

confidence: 99%

Reactive Molecular Dynamics Simulations to Investigate the Shock Response of Liquid Nitromethane

Islam

Strachan

2019

J. Phys. Chem. C

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“…Multi-objective optimization of force field parameters and uncertainty quantification can be merged to provide a standardized UQ capability for reactive simulations [55]. In case of extremely fast reactions of thermal deflagration, the velocity of propagation can make a significant difference unless the time steps for RMD simulations are restricted to 0.1 fs and below for obtaining consistent results [64,65,66]. Subsequently, mirrored atomistic RMD and continuum simulations show that average of rates, temperature, and pressure can also carry significant differences due to atomistic scale fluctuations in averages calculated using a control volume (CV) approach and propagated to the continuum scale [65,67,68].…”

Section: Uncertainty Quantification Approaches For MD Simulationsmentioning

confidence: 99%

“…In case of extremely fast reactions of thermal deflagration, the velocity of propagation can make a significant difference unless the time steps for RMD simulations are restricted to 0.1 fs and below for obtaining consistent results [64,65,66]. Subsequently, mirrored atomistic RMD and continuum simulations show that average of rates, temperature, and pressure can also carry significant differences due to atomistic scale fluctuations in averages calculated using a control volume (CV) approach and propagated to the continuum scale [65,67,68]. Integration schemes and polynomial fitting of rates of reactions are prone to their own numerical error.…”

Section: Uncertainty Quantification Approaches For MD Simulationsmentioning

confidence: 99%

Uncertainty Quantification in Atomistic Modeling of Metals and Its Effect on Mesoscale and Continuum Modeling: A Review

Gabriel

Paulson

Duong

et al. 2020

JOM

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The design of next-generation alloys through the Integrated Computational Materials Engineering (ICME) approach relies on multi-scale computer simulations to provide thermodynamic properties when experiments are difficult to conduct. Atomistic methods such as Density Functional Theory (DFT) and Molecular Dynamics (MD) have been successful in predicting properties of never before studied compounds or phases. However, uncertainty quantification (UQ) of DFT and MD results is rarely reported due to computational and UQ methodology challenges. Over the past decade, studies have emerged that mitigate this gap. These advances are reviewed in the context of thermodynamic modeling and information exchange with mesoscale methods such as Phase Field Method (PFM) and Calculation of Phase Diagrams (CALPHAD). The importance of UQ is illustrated using properties of metals, with aluminum as an example, and highlighting deterministic, frequentist and Bayesian methodologies. Challenges facing routine uncertainty quantification and an outlook on addressing them are also presented.

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“…This study aimed at investigating the flame propagation and overpressure effect where the effect of turbulence is dominant. It can be very challenging to model the detailed chemical reactions in deflagration, which is due to the nonlinear relation with chemical and thermodynamic states [39,40]. The deflagration flames are often characterized by propagating thin reaction flame front which is much smaller than the turbulent scales and is strongly affected by turbulence (causing flame wrinkling and complex thermochemical-turbulence interactions).…”

Section: Model Theory Basismentioning

confidence: 99%

Dynamic Simulation on Deflagration of LNG Spill

Sun

Guo

Pareek

2019

Journal of Combustion

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The deflagration characteristics of premixed LNG vapour-air mixtures with different mixing ratios were quantitatively and qualitatively investigated by using CFD (computational fluid dynamics) method. The CFD model was initially established based on theoretical analysis and then validated by a lab-scale deflagration experiment. The flame propagation behaviour, pressure-time history, and flame speed were compared with the experimental data, upon which a good agreement was achieved. A large-scale deflagration fire during LNG bunkering process was conducted using the model to investigate the flame development and overpressure effects. Mesh independence and time scale were tested in order to obtain the suitable grid resolution and time step. Deflagration cases with two different LNG vapour volume fractions, i.e., 10.4% and 15.0%, were simulated and compared. The one with a volume fraction of 10.4% which was around stoichiometric mixing ratio had the highest flame propagating speed. High flame velocity observed in the simulation was coupled with the thin flame front where overpressure occurred. The CFD model could capture the main features of deflagration combustion and account for LNG fire hazard which could provide an in-depth insight when dealing with complicated cases.

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Observation of deflagration wave in energetic materials using reactive molecular dynamics

Cited by 22 publications

References 53 publications

Reactive Molecular Dynamics Simulations to Investigate the Shock Response of Liquid Nitromethane

Reactive Molecular Dynamics Simulations to Investigate the Shock Response of Liquid Nitromethane

Uncertainty Quantification in Atomistic Modeling of Metals and Its Effect on Mesoscale and Continuum Modeling: A Review

Dynamic Simulation on Deflagration of LNG Spill

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