Reactive Shock Research Articles

A generalization of the shock invariant relationship

Shock invariant relationship, which was conceived for inert shock waves to derive the 4th power relationship between shock pressure and maximum strain rate, is generalized for reactive shock waves such as Chapman–Jouget detonation and shock-induced vaporization. The generalization, based on the first-order reaction models, is a power function relationship between overall dissipated energy (Δedis) and reaction time Δτ such that ΔedisΔτ1/α=constant, where the power coefficient α is found to be in the range of 2/3–4. Experimental data, though scarce, are consistent with the generalization. Implication of the generalization for inert shocks is also considered and suggests a broad range of the 4th power coefficient including an inequality equation that constrains the shock and particle velocity relationship.

Influence of electric potential-induced by atmospheric pressure plasma on cell response

Plasma irradiation leads not only active species, but also reactive chemical species, ultraviolet light, electric fields, magnetic fields, and shock waves. To date the effects of reactive chemical species have been mainly discussed. To understand the biological effect caused by an electric potential induced with an atmospheric-pressure plasma, the behavior of cell stimulated by electric potential was investigated using HeLa cell. The cell concentration assay revealed that less than 20% of cells inactivated by potential stimulation and the remained cells proliferate afterward. Fluorescent microscopic observation revealed that potential stimulation is appreciable to transport the molecules through membrane. These results show that potential stimulation induces intracellular and extracellular molecular transport, while the stimulation has a low lethal effect. A possible mechanism for this molecular transport by potential stimulation was also shown using numerical simulation based on an equivalent circuit of the experimental system including adhered HeLa cell. The potential formation caused by plasma generation is decisive in the contribution of plasma science to molecular biology and the elucidation of the mechanism underlying a biological response induction by plasma irradiation.

Investigation of the inverse piezoelectric effect of synchrotron light source imaging of electrical stimulation on the fate of nano stem cells and its role and application in regenerative medicine and cancer treatment

The presence of electrical activity in body organs such as the nervous system, heart and bones has caused one of the most widely used treatment methods called electrotherapy to be widely used, especially in the relief of underlying pain. On the other hand, the progress of medical science in the field of nano stem cells and regenerative medicine has created many promises in treatment. Also, recently, treatments based on electric field have been widely used in cancer treatment. The main issues in regenerative medicine are the proliferation of nano stem cells to the required extent and directing them towards the differentiation of the target tissue. Electric field (EF) stimulation can play an important role in creating appropriate nano stem cell responses and directing nano stem cell differentiation towards osteogenesis/neuronogenesis/cardiomyogenesis. The electric field with nanosecond pulse as well as the electric field for tumor therapy have attracted a lot of attention for the treatment of cancer. Major signaling pathways and cellular responses elicited by electrical stimulation include reactive oxygen species and heat shock proteins, fluctuations in intracellular calcium ion concentration, ATP production, clustering or reaggregation of cell surface receptors., reconstruction of the cytoskeleton that affect the fate of the nano stem cell. Also, the lack of pain, ease and reasonable price have made cancer treatment with electric field more and more popular. In this research, an attempt has been made to briefly review the effects of electrical signals on the behavior of nano stem cells, as well as examples of their therapeutic effects in the treatment of tissue lesions and cancer. Schematic of the inverse piezoelectric effect of synchrotron light source imaging of electrical stimulation on the fate of nano stem cells and its role and application in regenerative medicine and cancer treatment.

Experimental investigation of shock response to an insensitive explosive under double-shock wave

A new integrated velocimetry system that includes terahertz-wave-based Doppler velocimetry (TDV) and a multiplied electromagnetic particle velocity gauge (EMV) is demonstrated by measuring the particle velocity history and the corresponding shock-to-detonation transition (SDT) distance in double-shock experiments of insensitive explosive 1,3,5-triamino-2,4,6-trinitrobenzene (TATB)-2. This system overcomes the defects in resolution, testing distance, particle velocity measurement history, and shock-wave capture when TDV or EMV are used separately in double-shock experiments. The effectiveness of the integrated velocimetry system is verified via double-shock experiments, and the deviation of shock wave displacement is less than 6%. Furthermore, the desensitization effects of TATB-2 are determined by comparing the initiation behavior for the double-shock and sustained-pulse experiments. Results indicate that the longer the time of the unreactive preshock wave, the stronger the desensitization effects. Further, the reactive main shock wave in the double-shock experiment can weaken the desensitization effects of the double-shock wave.

Abscisic Acid Improves Rice Thermo-Tolerance by Affecting Trehalose Metabolism.

Heat stress that occurs during the flowering stage severely decreases the rice (Oryza sativa L.) seed-setting rate. This damage can be reversed by abscisic acid (ABA), through effects on reactive oxygen species, carbohydrate metabolism, and heat shock proteins, but the exact role of trehalose and ATP in this process remains unclear. Two rice genotypes, namely, Zhefu802 (heat-resistant plant, a recurrent parent) and its near-isogenic line (faded green leaf, Fgl, heat-sensitive plant), were subjected to 38 °C heat stress after being sprayed with ABA or its biosynthetic inhibitor, fluridone (Flu), at the flowering stage. The results showed that exogenous ABA significantly increased the seed-setting rate of rice under heat stress, by 14.31 and 22.40% in Zhefu802 and Fgl, respectively, when compared with the H2O treatment. Similarly, exogenous ABA increased trehalose content, key enzyme activities of trehalose metabolism, ATP content, and F1Fo-ATPase activity. Importantly, the opposite results were observed in plants treated with Flu. Therefore, ABA may improve rice thermo-tolerance by affecting trehalose metabolism and ATP consumption.

Evaluation of UV-B Ameliorating Properties of Indigenous Plants Ashwagandha Withania somnifera (Dunal), Amla Emblica officinalis (Gaertn), and Prickly Chaff Flower Achyranthes aspera (L.) Supplemented Diets in Prior UV-B Exposed Catla catla

Ultraviolet B (UV-B) radiation is a potent environmental stressor and it severely affects the survival, growth, and physiology of aquatic organisms. The UV-B protective properties of three herbal ingredients enriched diets were evaluated in pre-exposedCatla catla. Fish (70.38 ± 1.18 g) were divided into five sets with three replicates each. Four sets were exposed to UV-B (80 µW/cm2) for an initial 10 days (20 min/day), and the fifth one remained unexposed (control). On day 11, feeding with enriched diets started. These diets were: diet 1 (D1) containingWithania somnifera(0.5%) root powder, diet 2 (D2) containingEmblica officinalis(1.25%) fruit powder, diet 3 (D3) containing seeds ofAchyranthes aspera(0.5%), and diet 4 (D4) control. There were two batches of D4 diet-fed fish, D4a, UV-B exposed, and D4b unexposed. Blood and tissue samples were collected on days 0, 7, 14, and 21 of feeding. The average weight reduced 26.32% in UV-B exposed catla compared to the unexposed one on day 0. Among the exposed fish, average weight was significantly higher in D3 compared to others throughout the study period. Significantly lower nitric oxide synthase (NOS) and higher thiobarbituric acid reactive substances (TBARS), carbonyl protein, superoxide dismutase (SOD), and heat shock proteins (Hsp) 70 and 90 were observed in D4a compared to the enriched diet fed catla. The NOS level was significantly higher in D3 on day 21. The TBARS level was significantly lower in D3 on days 7 and 14 and in D2 and D3 on day 21. The carbonyl protein, SOD, and Hsp70 levels were always significantly lower in D3 compared to others, and D2 followed D3 treatment. Hsp 90 was significantly lower in D2 compared to others on day 7 and in D3 on days 14 and 21. All three enriched diets helped the fish overcome the harmful effect of UV-B radiation, and the D3 diet-fed fish showed the best performance.

A theoretical method for solving shock relations coupled with chemical equilibrium and its applications

In this study, a theoretical method is proposed to solve shock relations coupled with chemical equilibrium. Not only shock waves in dissociated flows but also detonation waves in combustive mixtures can be solved. The global iterative solving process is specially designed to mimic the physical and chemical process in reactive shock waves to ensure good stability and fast convergence in the proposed method. Within each global step, the single-variable equations of normal and oblique shock relations are derived and solved with the Newton iteration method to reduce the complexity of the problems, and the minimization of free energy method of NASA (National Aeronautics and Space Administration) is adopted to solve equilibrium compositions. It is demonstrated that the convergent process is stable and very close to the real chemical-kinetic process, and high accuracy is achieved in the solutions of normal and oblique reactive shock waves. Moreover, the proposed theoretical method has also been applied to many problems associated with reactive shocks, including the stability of oblique detonation wave, bow detonation over a sphere, and shock reflection in dissociated air. The great importance of using chemical equilibrium to theoretically predict the theoretical range of the wedge angle for a standing oblique detonation wave (the standing window of the oblique detonation wave), the stand-off distance of bow detonation wave and the transition criterion of shock reflection in dissociated air with high accuracy have been addressed.

High D-arabitol production with osmotic pressure control fed-batch fermentation by Yarrowia lipolytica and proteomic analysis under nitrogen source perturbation

D-arabitol, a five-carbon sugar alcohol, is widely used in food and pharmacy industry as a lower calorie sweetener or intermediate. Appropriate osmotic pressure was confirmed to facilitate polyol production by an osmophilic yeast strain of Yarrowia lipolytica with glycerol. In this study, an osmotic pressure control fed-batch fermentation strategy was used for high D-arabitol producing by Y. lipolytica ARA9 with crude glycerol. Glycerol was added to the broth quantitatively not only as a substrate but also as an osmotic agent. Meanwhile, NH3·H2O was fed as a nitrogen source and pH regulator. The maximum D-arabitol production reached 118.5 g/L at 108 h with the yield of 0.49 g/g and productivity of 1.10 g/L/h, respectively. Furthermore, a comparative proteomic analysis was used to study the cellular responses under excess and deficient nitrogen sources. Thirty-one differentially expressed protein spots belonging to seven different biological processes were identified. Excess nitrogen source enhanced gluconeogenesis and pentose phosphate pathways, both of which were involved in arabitol synthesis. In addition, cell growth was facilitated by increased expression of nucleotide and structural proteins. Enhanced energy and NADPH biosynthesis were employed to create a reductive environment and quell reactive oxygen species, improving D-arabitol production. Nitrogen deficiency resulted in cell rescue and stress response mechanisms such as reactive oxygen species elimination and heat shock protein response. The identified differentially expressed proteins provide information to reveal the mechanisms of the cellular responses under nitrogen source perturbation, and also provide guidance to improve D-arabitol production in metabolic engineering or process optimization methodologies.

Numerical Investigation on Combustion-Enhancement Strategy in Shock–Fuel Jet Interaction

Multidimensional numerical simulations are performed to investigate the evolution and formation of unburned fuels for a shock–fuel jet interaction scenario. A full set of Navier–Stokes equations with detailed chemical mechanisms are solved, and the results are analyzed through the Lagrangian method with the goal of improving combustion efficiency in supersonic flows. The flame morphology of a two-dimensional (2-D) non-premixed reactive shock–bubble interaction is first simulated and studied, in which unburned hydrogen is found to prevent efficient combustion. By applying the Lagrangian particle tracking method, most of the unburned hydrogen wrapped into the primary vortex turns out to be initially located upon the symmetry line of the bubble. Motivated by the idea of breaking the primary vortex, this study designs a novel geometry of a concentric bubble, which improves combustion efficiency to 94.4% in contrast to a solid fuel bubble (74%) due to multivortex interaction and a thick bridge structure. With the consistency between qualitative and quantitative 2-D and three-dimensional (3-D) flow dynamics, the idea of a 2-D concentric-bubble configuration is effectively extended to a 3-D coaxial jet interacting with oblique shock despite the existence of Kelvin–Helmholtz instability.

Mitochondria-Targeting Enhanced Phototherapy by Intrinsic Characteristics Engineered "One-for-All" Nanoparticles.

Mitochondria-targeted synergistic therapy, including photothermal (PTT) and photodynamic therapy (PDT), has aroused wide attention due to the high sensitivity to reactive oxygen species (ROS) and heat shock of mitochondria. However, most of the developed nanosystems for the combinatorial functions require the integration of different components, such as photosensitizers and mitochondria-targeted molecules. Consequently, it indispensably requires sophisticated design and complex synthetic procedures. In this work, a well-designed Bi2S3-based nanoneedle, that localizes to mitochondria and produces extra ROS with inherent photothermal effect, was reported by doping of Fe (denoted as FeBS). The engineered intrinsic characteristics certify the capacity of such "one-for-all" nanosystems without additional molecules. The lipophilicity and surface positive charge are demonstrated as crucial factors for specifical mitochondria targeting. Significantly, Fe doping overcomes the disadvantage of the narrow band gap of Bi2S3 to prevent the fast recombination of electron-hole, hence resulting in the generation of ROS for PDT. The "one-for-all" nanoparticles integrate with mitochondria-targeting and synergistic effect of PDT and PTT, thus exhibit enhanced therapeutic effect and inhibit the growth of tumors observably. This strategy may open a new direction in designing the mitochondria-targeted materials and broadening the properties of inorganic semiconductor materials for satisfactory therapeutic outcomes.

Modelling of a spherical deflagration at constant speed

We build in this paper a numerical solution procedure to compute the flow induced by a spherical flame expanding from a point source at a constant expansion velocity, with an instantaneous chemical reaction. The solution is supposed to be self-similar and the flow is split in three zones: an inner zone composed of burnt gases at rest, an intermediate zone where the solution is regular and the initial atmosphere composed of fresh gases at rest. The intermediate zone is bounded by the reactive shock (inner side) and the so-called precursor shock (outer side), for which Rankine-Hugoniot conditions are written; the solution in this zone is governed by two ordinary differential equations which are solved numerically. We show that, for any admissible precursor shock speed (and, in some cases, for a reaction heat large enough), the construction combining this numerical resolution with the exploitation of jump conditions is unique, and yields decreasing pressure, density and velocity profiles in the intermediate zone. In addition, the reactive shock speed is larger than the velocity on the outer side of the shock, which is consistent with the fact that the difference between these two quantities is the so-called flame velocity, i.e. the (relative) velocity at which the chemical reaction progresses in the fresh gases. Finally, we also observe numerically that the function giving the flame velocity as a function of the precursor shock speed is increasing; this allows to embed the resolution in a Newton-like procedure to compute the flow for a given flame speed (instead of for a given precursor shock speed). The resulting numerical algorithm is applied to stoichiometric hydrogen-air mixtures.

Micro-combustion modelling with RBF-FD: A high-order meshfree method for reactive flows in complex geometries

New micro-devices, such as unmanned aerial vehicles or micro-robots, have increased the demand of a new generation of small-scale combustion power system that go beyond the energy-density limitations of batteries or fuel cells. The characteristics short residence times and intense heat losses reduce the efficiency of combustion-based devices, a key factor that requires of an acute modelling effort to understand the competing physicochemical phenomena that hamper their efficient operation. With this objective in mind, this paper is devoted to the development of a high-order meshfree method to model combustion inside complex geometries using radial basis functions-generated finite differences (RBF-FD) based on polyharmonic splines (PHS) augmented with multivariate polynomials (PHS+poly). In our model, the combustion chamber of a micro-rotary engine is simulated by a system of unsteady reaction-diffusion equations coupled with a steady flow passing a bidimensional stenotic channel of great slenderness. The conversion efficiency is characterized by identifying the different combustion regimes that emerged as a function of the ignition point. We show that PHS+poly based RBF-FD is able to achieve high-order algebraic convergence on scattered node distributions, enabling for node refinement in key regions of the fluid domain. This feature makes it specially well adapted to integrate problems in irregular geometries with front-like solutions, such as reactive fronts or shock waves. Several numerical tests are carried out to demonstrate the accuracy and effectiveness of our approach.

The protective role of PHB and its degradation products against stress situations in bacteria.

Many bacteria produce storage biopolymers that are mobilized under conditions of metabolic adaptation, for example, low nutrient availability and cellular stress. Polyhydroxyalkanoates are often found as carbon storage in Bacteria or Archaea, and of these polyhydroxybutyrate (PHB) is the most frequently occurring PHA type. Bacteria usually produce PHB upon availability of a carbon source and limitation of another essential nutrient. Therefore, it is widely believed that the function of PHB is to serve as a mobilizable carbon repository when bacteria face carbon limitation, supporting their survival. However, recent findings indicate that bacteria switch from PHB synthesis to mobilization under stress conditions such as thermal and oxidative shock. The mobilization products, 3-hydroxybutyrate and its oligomers, show a protective effect against protein aggregation and cellular damage caused by reactive oxygen species and heat shock. Thus, bacteria should have an environmental monitoring mechanism directly connected to the regulation of the PHB metabolism. Here, we review the current knowledge on PHB physiology together with a summary of recent findings on novel functions of PHB in stress resistance. Potential applications of these new functions are also presented.

Hollow magnetic nanosystem-boosting synergistic effect between magnetic hyperthermia and sonodynamic therapy via modulating reactive oxygen species and heat shock proteins

As a promising treatment modality with spatial and temporal control, alternating magnetic field (AMF) triggered magnetic hyperthermal therapy (MHT) shows broad and promising applications to overcome the drawbacks of traditional focal therapies in combating cancer. However, the MHT efficacy is still not satisfactory with the presence of heat shock proteins (HSPs). In addition, sustained tumor hypoxia haunts practical implications for the treatment of solid tumors. Herein, a novel magnetic nanosystem composed of hollow iron oxide nanoparticles (HIONs), Fe3O4, and sonosensitizers, hematoporphyrin (HP) was rationally designed and successfully synthesized. The hollow HIONs show a large inner cavity for loading sonosensitizer molecules and possess nanozyme activity for catalyzing decomposition of endogenous overexpressed hydrogen peroxide (H2O2) to produce molecular oxygen (O2) that can overcome tumor hypoxia, thus augmenting the sonodynamic therapy (SDT)-induced highly toxic reactive oxygen species (ROS) production for efficient cancer cell apoptosis. Importantly, the generated ROS can also activates the cleavage of HSPs that further eliminate themotolerance and facilitates MHT efficacy. The synergistic catalysis-enhanced SDT efficiency and MHT effect realized most potent tumor suppression efficacy. This work develops a versatile nanoplatform for a multifunctional strategy and broadens the biological applications by rationally designing their structure.

Phase I study of a new concept cancer vaccine composed artificial intelligence (AI)-designed shared-antigen peptides plus combined synergistically activating antigen-specific CTL reaction (CYT001) in patients with advanced hepatocellular carcinoma (CRESCENT 1).

TPS595 Background: CYT001 (CYTLIMIC Inc.) is a novel cancer vaccine involving artificial intelligence (AI)-designed shared-antigen peptides and optimal combined adjuvants that boost the cancer-immunity cycle. The two multi-HLA reactive peptides heat shock protein 70 (HSP70) and glypican 3 (GPC3) were screened by an AI-based prediction system according to the proteome, mRNA, and histopathology data fromhuman samples. These immunogenic peptides were confirmed to show cross-reactivity to HLA-A 24:02, 02:01, and 02:06. Poly-ICLC (Oncovir Inc.) binds to Toll-like receptor 3 (TLR3) and melanoma differentiation antigen 5 (MDA5) on antigen-presenting cells (APCs)and activates APCs. LAG-3Ig (Immutep Inc.) binds to the major histocompatibility complex (MHC) class II molecules of APCs and activates APCs. Both poly-ICLC and LAG-3Ig synergistically activate antigen-specific CTL reactions as effective combination adjuvants. The present study aims to evaluate the safety and tolerability of CYT001 (mixture of HSP70 peptide [2.0 mg], GPC3 peptide [2.0 mg], poly-ICLC [1.0 mg], and LAG-3Ig [1.4 mg]) in patients with advanced hepatocellular carcinoma (HCC). Methods: This is a single-center, phase 1, open-label, single-arm, investigator-initiated clinical trial of CYT001 for advanced HCC patients with no eligible standard systemic therapy, Child–Pugh A liver disease, and HLA-A 24:02, 02:01, or 02:06. Enrolled patients will receive CYT001 as a subcutaneous injection on days 1, 8, 15, and 21 in the 1st and 2nd cycles, days 1 and 15 in the 3rd and 4th cycles, and day 1 in the 5th cycle or later of 28-day cycles. The primary endpoint is dose-limiting toxicity, and the secondary endpoints are safety and the response rate. The transition of the CTL reactions of both the HSP70 and GPC3 peptides will be evaluated using blood samples of the subjects. Exploratory analyses include investigation of candidate biomarkers for treatment efficacy using liver tumor biopsy samples (baseline and after the 1st cycle) and blood samples (baseline and every days of administration). Clinical trial information: jRCT2031190072.

Improvement of Thermotolerance of Zymomonas mobilis by Genes for Reactive Oxygen Species-Scavenging Enzymes and Heat Shock Proteins.

Thermotolerant genes, which are essential for survival at a high temperature, have been identified in three mesophilic microbes, including Zymomonas mobilis. Contrary to expectation, they include only a few genes for reactive oxygen species (ROS)-scavenging enzymes and heat shock proteins, which are assumed to play key roles at a critical high temperature (CHT) as an upper limit of survival. We thus examined the effects of increased expression of these genes on the cell growth of Z. mobilis strains at its CHT. When overexpressed, most of the genes increased the CHT by about one degree, and some of them enhanced tolerance against acetic acid. These findings suggest that ROS-damaged molecules or unfolded proteins that prevent cell growth are accumulated in cells at the CHT.

Effect of light intensity on survival, growth and physiology of rohu, Labeo rohita (Cyprinidae) fry

Purpose: Light intensity is one of the important environmental factors that have strong influence on larviculture. Culture of fish at high intensity of light generates harmful radicals in the body that can compromise their health and production. The present study aims to evaluate the effect of various light intensities on the physiology of rohu Labeo rohita fry.Materials and Methods: Rohu fry (13.56 ± 0.4 mg) were exposed at five different light intensities: 0.17 ± 0.005 (Lc, control), 1.45 ± 0.23 (L1), 2.69 ± 0.47 (L2), 3.93 ± 0.72 (L3) and 5.06 ± 0.95 Wm−2 (L4). After 90 days of culture, rohu were harvested.Results and Conclusions: A 2-5% mortality of rohu was recorded in L3 and L4 treatments. The average weight and specific growth rate were significantly (p < .05) higher in Lc treatment compared to others. The light intensity and swimming activity of rohu showed direct relationship, whereas, light intensity showed inverse relation with nitric oxide synthase and reduced glutathione levels. Significantly (p < .05) higher glutathione S-transferase and glutathione peroxidase activies were found in rohu exposed at L4 treatment. Higher light intensities resulted in oxidative stress in the muscles of rohu. Thiobarbituric acid reactive substances, carbonyl protein and heat shock protein 70 were significantly (p < .05) higher in rohu exposed at L4 compared to other treatments. Exposure of rohu fry to intense light resulted into physiological stress and immunosupression.

Forging of Hierarchical Multiscale Capabilities for Simulation of Energetic Materials

AbstractWe present new capabilities for investigation of microstructure in energetic material response for both explicit large‐scale and multiscale simulations. We demonstrate the computational capabilities by studying the effect of porosity on the reactive shock response of a coarse‐grain (CG) model of the energetic material cyclotrimethylene trinitramine (RDX), the non‐reactive equation of state for a porous representative volume element (RVE) of CG RDX, and utilization of available supercomputing resources for speculative sampling to accelerate hierarchical multiscale simulations. Small amounts of porosity (up to 4 %) are shown to have significant effect on the initiation of reactive CG RDX using large‐scale reactive dissipative particle dynamics simulations. Non‐reactive RVEs are shown to undergo a porosity‐dependent pore collapse at hydrostatic conditions, and an existing automation framework is shown to be easily modified for the incorporation of microstructure while retaining reliable convergence properties. A novel predictive sampling method based on use of kernel density estimators is shown to effectively accelerate time‐to‐solution in a multiscale simulation, scaling with free CPU cores, while making no assumptions about the underlying physics for the data being analyzed. These multidisciplinary studies of distinct yet connected problems combine to provide methodological insights for high‐fidelity modeling of reactive systems with microstructure.

Modelling the Fluctuations of Reactive Shock Waves in Heterogeneous Solid Explosives as Stochastic Processes

AbstractWhile current phenomenological burn models are useful for describing the average or bulk reactive flow behaviour of heterogeneous explosives, one fundamental weakness inherent to these models is the loss of detailed microstructural information at the scale of the calculation. In order to include the effects of the microstructure, and in particular the underlying material heterogeneities that influence the build‐up to detonation, a new paradigm is put forth for modelling sub‐grid, reaction‐induced fluctuations (i. e. “hot spots”) at the continuum level. This modelling approach assumes that the reaction rate is stochastic, rather than deterministic, and it uses Langevin‐type equations with a mathematical framework built upon Itô calculus and Lambourn's CIM model for shocked heterogeneous explosives. This approach follows directly from our previous letter, Ref. [1], and is inspired by the probability density function (pdf) methods used in turbulent reactive flows. Here, the stochastic burn model is derived, implemented, and exercised far beyond what has been shown in previous work. New hydrocode simulation results demonstrate the role of stochastic fluctuations during shock initiation; these fluctuations are approximated by collections of discrete particles, that evolve with drift (i. e. deterministic) and diffusion (i. e. stochastic) coefficients. Additionally, the particle values are propagated and averaged to calculate the heat release, yield strength, and material impedance in each computational cell. Hydrocode simulation results further show how the fluctuating hot spot energy may or may not be transmitted to the wave front, and result in a detonation wave‐like structure. The fundamental stochastic nature of this model permits simulations to have varying outcomes with the same initial conditions; this allows for go/no‐go estimation (e. g., marginal or failed detonations), which might possibly be calibrated using the statistical distributions from real materials. Mesoscale calculations of shocked heterogeneous explosives also show that these fluctuations are physically justified (i. e., Ref. [2]), and it is hypothesized that the pdf functions provide a link between the meso(grain) and continuum scales for practical engineering calculations. Thus, our approach is a paradigm shift for building efficient, reduced order continuum burn models, that represent the sub‐grid stochastic behaviour of shocked heterogeneous solid explosives.

Letter: Modeling reactive shock waves in heterogeneous solids at the continuum level with stochastic differential equations

A new paradigm is introduced for modeling reactive shock waves in heterogeneous solids at the continuum level. Inspired by the probability density function methods from turbulent reactive flows, it is hypothesized that the unreacted material microstructures lead to a distribution of heat release rates from chemical reaction. Fluctuations in heat release, rather than velocity, are coupled to the reactive Euler equations which are then solved via the Riemann problem. A numerically efficient, one-dimensional hydrocode is used to demonstrate this new approach, and simulation results of a representative impact calculation (inert flyer into explosive target) are discussed.