scholarly journals An Energetic Model for Detonation of Granulated Solid Propellants

Energies ◽  
2019 ◽  
Vol 12 (23) ◽  
pp. 4459 ◽  
Author(s):  
López-Munoz ◽  
García-Cascales ◽  
Velasco ◽  
Otón-Martínez
Keyword(s):  
Energetic Materials ◽  
Solid Phase ◽  
Constitutive Relations ◽  
Particle Interaction ◽  
Combustion Process ◽  
Numerical Schemes ◽  
Mass Generation ◽  
Interphase Heat Transfer ◽  
Early Stages ◽  
Granular Solid

Unexpected detonation of granular solid energetic materials is a key safety issue in the propellants manufacturing industry. In this work, a model developed for the characterization of the early stages of the detonation process of granular solid energetic materials is presented. The model relies on a two-phase approach which considers the conservation equations of mass, momentum, and energy and constitutive relations for mass generation, gas-solid particle interaction, interphase heat transfer, and particle-particle stress. The work considers an extension of approximated Riemann solvers and Total Variation Diminishing (TVD) schemes to the solid phase for the numerical integration of the problem. The results obtained with this model show a good agreement with data available in the literature and confirm the potential of the numerical schemes applied to this type of model. The results also permit to assess the effectiveness of different numerical schemes to predict the early stages of this transient combustion process.

The Investigation of a Fluid-Solid Interaction Mathematical Model under Combined Convective Jeffrey Flow and Radiation Effect Embedded Newtonian Heating as the Thermal Boundary Condition over a Vertical Stretching Sheet

2020 ◽  
Vol 399 ◽  
pp. 65-75 ◽  
Author(s):  
Abdul Rahman Mohd Kasim ◽  
Nur Syamilah Arifin ◽  
Syazwani Mohd Zokri ◽  
Mohd Zuki Salleh
Keyword(s):  
Differential Equation ◽  
Boundary Condition ◽  
Stretching Sheet ◽  
Solid Phase ◽  
Particle Interaction ◽  
Thermal Boundary Condition ◽  
Dust Particles ◽  
Jeffrey Fluid ◽  
Physical Parameters ◽  
Newtonian Heating

The investigation on the interaction between solid and fluid under combined convective flow has been carried out mathematically. The Jeffrey fluid model is taken as the fluid phase and the model is being embedded with the dust particles (solid phase). This two-phase model is constructed by introducing the fluid-particles interaction forces in the momentum equations of the fluid and dust phases, respectively. The natural and forced convections together with the aligned magnetic field are considered on the fluid flow. Also, the Newtonian heating as thermal boundary condition is induced on the vertical stretching sheet. In order to reduce the complexity of the model, the governing equations are transformed from partial differential equation into ordinary differential equation via suitable similarity transformation. The solutions are obtained in terms of velocity and temperature profiles for the fluid and particles phases respectively whereby the Keller-box method is utilized to obtain the desired outcomes. The influences of several significant physical parameters are visualized graphically to clarify the flow and heat transfer characteristic for both phases. The investigation found that the fluid’s velocity is affected by the presence of the dust particles which led to decelerate the fluid transference. The present flow model is able to be compared with the single-phase fluid cases if the fluid-particle interaction parameter is ignored.

scholarly journals Enskog kinetic theory for monodisperse gas–solid flows

2012 ◽  
Vol 712 ◽  
pp. 129-168 ◽  
Author(s):  
V. Garzó ◽  
S. Tenneti ◽  
S. Subramaniam ◽  
C. M. Hrenya
Keyword(s):  
Reynolds Number ◽  
Kinetic Theory ◽  
Gas Phase ◽  
Parameter Space ◽  
Shear Viscosity ◽  
Solid Phase ◽  
Constitutive Relations ◽  
Solid Particles ◽  
Analytical Treatment ◽  
Starting Point

AbstractThe Enskog kinetic theory is used as a starting point to model a suspension of solid particles in a viscous gas. Unlike previous efforts for similar suspensions, the gas-phase contribution to the instantaneous particle acceleration appearing in the Enskog equation is modelled using a Langevin equation, which can be applied to a wide parameter space (e.g. high Reynolds number). Attention here is limited to low Reynolds number flow, however, in order to assess the influence of the gas phase on the constitutive relations, which was assumed to be negligible in a previous analytical treatment. The Chapman–Enskog method is used to derive the constitutive relations needed for the conservation of mass, momentum and granular energy. The results indicate that the Langevin model for instantaneous gas–solid force matches the form of the previous analytical treatment, indicating the promise of this method for regions of the parameter space outside of those attainable by analytical methods (e.g. higher Reynolds number). The results also indicate that the effect of the gas phase on the constitutive relations for the solid-phase shear viscosity and Dufour coefficient is non-negligible, particularly in relatively dilute systems. Moreover, unlike their granular (no gas phase) counterparts, the shear viscosity in gas–solid systems is found to be zero in the dilute limit and the Dufour coefficient is found to be non-zero in the elastic limit.

An Evaluation of Three-Dimensional Diarthrodial Joint Contact Using Penetration Data and the Finite Element Method

2001 ◽  
Vol 123 (4) ◽  
pp. 333-340 ◽  
Author(s):  
W. L. Dunbar, ◽  
K. U¨n ◽  
P. S. Donzelli ◽  
R. L. Spilker
Keyword(s):  
Finite Element ◽  
Boundary Conditions ◽  
Solid Phase ◽  
Constitutive Relations ◽  
Three Dimensional ◽  
Contact Boundary ◽  
Element Analysis ◽  
Joint Contact ◽  
Three Dimensional Finite Element

We have developed an approximate method for simulating the three-dimensional contact of soft biphasic tissues in diarthrodial joints under physiological loading. Input to the method includes: (i) kinematic information describing an in vitro joint articulation, measured while the cartilage is deformed under physiological loads, (ii) geometric properties for the relaxed (undeformed) cartilage layers, obtained for the analyses in this study via stereophotogrammetry, and (iii) material parameters for the biphasic constitutive relations used to represent cartilage. Solid models of the relaxed tissue layers are assembled in physiological positions, resulting in a mathematical overlap of the cartilage layers. The overlap distribution is quantified and converted via the biphasic governing equations into applied traction boundary conditions for both the solid and fluid phases for each of the contacting layers. Linear, biphasic, three-dimensional, finite element analysis is performed using the contact boundary conditions derived for each of the contacting layers. The method is found to produce results consistent with the continuity requirements of biphasic contact. Comparison with results from independent, biphasic contact analyses of axisymmetric problems shows that the method slightly underestimates the contact area, leading to an overestimation of the total traction, but yields a good approximation to elastic stress and solid phase displacement.

Sub-Grid Filtering Model for Multiphase Heat Transfer With Immersed Tubes

2014 ◽  
Author(s):  
William A. Lane ◽  
Emily M. Ryan ◽  
Avik Sarkar ◽  
Sankaran Sundaresan
Keyword(s):  
Heat Transfer ◽  
Solid Phase ◽  
Constitutive Relations ◽  
Conservation Equation ◽  
Coarse Grid ◽  
Computational Grids ◽  
Constitutive Function ◽  
Flow Simulations ◽  
Energy Conservation Equation ◽  
Functional Forms

Adequately resolving the hydrodynamics and heat transfer in gas-solid flow simulations typically requires computational grids on the order of 1–10 particle diameters. This requirement is not feasible for most full-scale applications. To overcome these impracticalities, we consider a sub-grid filtering approach where the microscopic heat transfer mechanisms are approximated through coarse grid simulations using constitutive relations. Using the open source CFD code Multiphase Flow with Interphase Exchanges (MFIX), we simulate a periodic unit cell domain with immersed horizontal heat transfer cylinders under varying solid-phase fractions and temperatures. The simulation results are averaged over the domain and are used to fit functional forms describing relations between the flow properties and input conditions. The result is a constitutive function that is added as a source term to the solid-phase energy conservation equation to approximate the effective heat transfer between the cylinders and flow with coarse grid simulations.

scholarly journals Effect of Local Thermal Nonequilibrium on the Stability of Natural Convection in an Oldroyd-B Fluid Saturated Vertical Porous Layer

2017 ◽  
Vol 139 (4) ◽  
Author(s):  
B. M. Shankar ◽  
I. S. Shivakumara
Keyword(s):  
Natural Convection ◽  
Solid Phase ◽  
Viscoelastic Fluids ◽  
Maxwell Fluid ◽  
Base Flow ◽  
Temperature Fields ◽  
Thermal Nonequilibrium ◽  
Interphase Heat Transfer ◽  
Local Thermal Nonequilibrium ◽  
The Stability

The effect of local thermal nonequilibrium (LTNE) on the stability of natural convection in a vertical porous slab saturated by an Oldroyd-B fluid is investigated. The vertical walls of the slab are impermeable and maintained at constant but different temperatures. A two-field model that represents the fluid and solid phase temperature fields separately is used for heat transport equation. The resulting stability eigenvalue problem is solved numerically using Chebyshev collocation method as the energy stability analysis becomes ineffective in deciding the stability of the system. Despite the basic state remains the same for Newtonian and viscoelastic fluids, it is observed that the base flow is unstable for viscoelastic fluids and this result is qualitatively different from Newtonian fluids. The results for Maxwell fluid are delineated as a particular case from the present study. It is found that the viscoelasticity has both stabilizing and destabilizing influence on the flow. Increase in the value of interphase heat transfer coefficient Ht, strain retardation parameter Λ2 and diffusivity ratio α portray stabilizing influence on the system while increasing stress relaxation parameter Λ1 and porosity-modified conductivity ratio γ exhibit an opposite trend.

FT-IR Standoff Detection of Thermally Excited Emissions of Trinitrotoluene (TNT) Deposited on Aluminum Substrates

2013 ◽  
Vol 67 (2) ◽  
pp. 181-186 ◽  
Author(s):  
John R. Castro-Suarez ◽  
Leonardo C. Pacheco-Londoño ◽  
Miguel Vélez-Reyes ◽  
Max Diem ◽  
Thomas J. Tague ◽  
...  
Keyword(s):  
Energetic Materials ◽  
Solid Phase ◽  
Detection System ◽  
Target Surface ◽  
Least Squares Regression ◽  
Passive Mode ◽  
Standoff Detection ◽  
Highly Energetic Materials ◽  
Aluminum Plates ◽  
Aluminum Substrates

A standoff detection system was assembled by coupling a reflecting telescope to a Fourier transform infrared spectrometer equipped with a cryo-cooled mercury cadmium telluride detector and used for detection of solid-phase samples deposited on substrates. Samples of highly energetic materials were deposited on aluminum substrates and detected at several collector-target distances by performing passive-mode, remote, infrared detection measurements on the heated analytes. Aluminum plates were used as support material, and 2,4,6-Trinitrotoluene (TNT) was used as the target. For standoff detection experiments, the samples were placed at different distances (4 to 55 m). Several target surface temperatures were investigated. Partial least squares regression analysis was applied to the analysis of the intensities of the spectra obtained. Overall, standoff detection in passive mode was useful for quantifying TNT deposited on the aluminum plates with high confidence up to target–collector distances of 55 m.

scholarly journals A multiscale description of growth and transport in biological tissues

2007 ◽  
Vol 34 (1) ◽  
pp. 51-86 ◽  
Author(s):  
A. Grillo ◽  
G.Y. Zingali ◽  
D.Y. Borrello ◽  
S.Z. Federico ◽  
W.Z. Herzog ◽  
...  
Keyword(s):  
Solid Phase ◽  
Pore Space ◽  
Constitutive Relations ◽  
Formal Solution ◽  
Fluid Phase ◽  
Biological Tissues ◽  
Chemical Substance ◽  
Anisotropic Growth ◽  
Field Equations ◽  
Chemical Substances

We study a growing biological tissue as an open biphasic mixture with mass exchange between phases. The solid phase is identified with the matrix of a porous medium, while the fluid phase is comprised of water, together with all the dissolved chemical substances coexisting in the pore space. We assume that chemical substances evolve according to transport mechanisms determined by kinematical and constitutive relations, and we propose to consider growth as a process able to influence transport by continuously varying the thermo-mechanic state of the tissue. By focusing on the case of anisotropic growth, we show that such an influence occurs through a continuous rearrangement of the tissue material symmetries. In order to illustrate this interaction, we restrict ourselves to diffusion-dominated transport, and we assume that the time-scales associated with growth and the transport process of interest are largely separated. This allows for performing an asymptotic analysis of the "field equations" of the system. In this framework, we provide a formal solution of the transport equation in terms of its associated Green's function, and we show how the macroscopic concentration of a given chemical substance is "modulated" by anisotropic growth. .

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