scholarly journals Numerical Method for Predicting the Blast Wave in Partially Confined Chamber

2018 ◽  
Vol 2018 ◽  
pp. 1-17 ◽  
Author(s):  
Wei-zheng Xu ◽  
Xiang-shao Kong ◽  
Cheng Zheng ◽  
Wei-guo Wu
Keyword(s):  
Blast Wave ◽  
Mach Reflection ◽  
Wave Interaction ◽  
Experimental Tests ◽  
Blast Waves ◽  
Finite Difference Schemes ◽  
Test Problems ◽  
Confined Space ◽  
Weighted Essentially Nonoscillatory ◽  
Fifth Order

Blast waves generated by cylindrical TNT explosives in partially confined chamber were studied numerically and experimentally. Based on the classical fifth-order weighted essentially nonoscillatory finite difference schemes (fifth-order WENO schemes), the 1D, 2D, and 3D codes for predicting the evolution of shock waves were developed. A variety of benchmark-test problems, including shock tube problem, interacting blast wave, shock entropy wave interaction, and double Mach reflection, were studied. Experimental tests of explosion events in a partially confined chamber were conducted. Then, the 3D code was employed to predict the overpressure-time histories of certain points of chamber walls. Through comparing, a good agreement between numerical prediction and experimental results was achieved. The studies in this paper provide a reliable means to predict the blast load in confined space.

Experimental and Numerical Investigation of Blast Wave Interaction With a Three Level Building

2017 ◽  
Vol 139 (11) ◽  
Author(s):  
Jacques Massoni ◽  
Laurent Biamino ◽  
Georges Jourdan ◽  
Ozer Igra ◽  
Lazhar Houas
Keyword(s):  
Shock Tube ◽  
Blast Wave ◽  
Wave Interaction ◽  
Wave Pattern ◽  
Blast Waves ◽  
Building Model ◽  
Experimental Part ◽  
Level Building ◽  
Blast Wave Interaction ◽  
Good Agreement

The present work shows that weak blast waves that are considered as being harmless can turn to become fatal upon their reflections from walls and corners inside a building. In the experimental part, weak blast waves were generated by using an open-end shock tube. A three level building model was placed in vicinity to the open-end of the used shock tube. The evolved wave pattern inside the building rooms was recorded by a sequence of schlieren photographs; also pressure histories were recorded on the rooms' walls. In addition, numerical simulations of the evolved flow field inside the building were conducted. The good agreement obtained between numerical and experimental results shows the potential of the used code for identifying safe and dangerous places inside the building rooms penetrated by the weak blast wave.

scholarly journals Analysis of Blast Wave Parameters Depending on Air Mesh Size

2018 ◽  
Vol 2018 ◽  
pp. 1-18 ◽  
Author(s):  
Hrvoje Draganić ◽  
Damir Varevac
Keyword(s):  
Numerical Simulations ◽  
Blast Wave ◽  
Large Scale ◽  
Wave Interaction ◽  
Mesh Size ◽  
Blast Waves ◽  
3D Environment ◽  
Close Range ◽  
Blast Wave Propagation ◽  
Optimal Mesh

Results of numerical simulations of explosion events greatly depend on the mesh size. Since these simulations demand large amounts of processing time, it is necessary to identify an optimal mesh size that will speed up the calculation and give adequate results. To obtain optimal mesh sizes for further large-scale numerical simulations of blast wave interactions with overpasses, mesh size convergence tests were conducted for incident and reflected blast waves for close range bursts (up to 5 m). Ansys Autodyn hydrocode software was used for blast modelling in axisymmetric environment for incident pressures and in a 3D environment for reflected pressures. In the axisymmetric environment only the blast wave propagation through the air was considered, and in 3D environment blast wave interaction and reflection of a rigid surface were considered. Analysis showed that numerical results greatly depend on the mesh size and Richardson extrapolation was used for extrapolating optimal mesh size for considered blast scenarios.

scholarly journals Guidelines to inform the generation of clinically relevant and realistic blast loading conditions for primary blast injury research

2021 ◽  
pp. bmjmilitary-2021-001796
Author(s):  
J W Denny ◽  
A S Dickinson ◽  
G S Langdon
Keyword(s):  
Blast Wave ◽  
Blast Loading ◽  
Wave Interaction ◽  
Blast Waves ◽  
Experimental Investigations ◽  
Loading Conditions ◽  
Primary Blast ◽  
Blast Overpressure ◽  
Engineering Theory ◽  
Blast Traumatic Brain Injury

‘Primary’ blast injuries (PBIs) are caused by direct blast wave interaction with the human body, particularly affecting air-containing organs. With continued experimental focus on PBI mechanisms, recently on blast traumatic brain injury, meaningful test outcomes rely on appropriate simulated conditions. Selected PBI predictive criteria (grouped into those affecting the auditory system, pulmonary injuries and brain trauma) are combined and plotted to provide rationale for generating clinically relevant loading conditions. Using blast engineering theory, explosion characteristics including blast wave parameters and fireball dimensions were calculated for a range of charge masses assuming hemispherical surface detonations and compared with PBI criteria. While many experimental loading conditions are achievable, this analysis demonstrated limits that should be observed to ensure loading is clinically relevant, realistic and practical. For PBI outcomes sensitive only to blast overpressure, blast scaled distance was demonstrated to be a useful parameter for guiding experimental design as it permits flexibility for different experimental set-ups. This analysis revealed that blast waves should correspond to blast scaled distances of 1.75<Z<6.0 to generate loading conditions found outside the fireball and of clinical relevance to a range of PBIs. Blast waves with positive phase durations (2–10 ms) are more practical to achieve through experimental approaches, while representing realistic threats such as improvised explosive devices (ie, 1–50 kg trinitrotoluene equivalent). These guidelines can be used by researchers to inform the design of appropriate blast loading conditions in PBI experimental investigations.

Plane blast wave interaction with an elongated straight and inclined heat-generated inhomogeneity

2018 ◽  
Vol 851 ◽  
pp. 245-267 ◽  
Author(s):  
S. Sembian ◽  
M. Liverts ◽  
N. Apazidis
Keyword(s):  
Blast Wave ◽  
High Speed ◽  
Quadratic Function ◽  
Wave Interaction ◽  
Numerical Data ◽  
Ambient Air ◽  
Blast Waves ◽  
Incident Plane ◽  
Gradual Loss ◽  
Two Factors

The unstable evolution of an elongated elliptically shaped inhomogeneity that is embedded in ambient air and aligned both normal and at an angle to an incident plane blast wave of impact Mach number 2.15 is investigated both experimentally and numerically. The elliptic inhomogeneities and the blast waves are generated using gas heating and exploding wire technique and their interaction is captured optically using shadowgraph method. While two symmetric counter-rotating vortices due to Richtmyer–Meshkov instability are observed for the straight interaction, the formation of a train of vortices similar to Kelvin–Helmholtz instability, introducing asymmetry into the flow field, are observed for an inclined interaction. During the early phase of the interaction process in the straight case, the growth of the counter-rotating vortices (based on the sequence of images obtained from the high-speed camera) and circulation (calculated with the aid of numerical data) are found to be linear in both space and time. Moreover, the normalized circulation is independent of the inhomogeneity density and the ellipse thickness, enabling the formulation of a unique linear fit equation. Conversely, the circulation for an inclined case follows a quadratic function, with each vortex in the train estimated to move with a different velocity directly related to its size at that instant. Two factors influencing the quadratic nature are identified: the reduction in strength of the transmitted shock thereby generating vortices with reduced vorticity, along with the gradual loss of vorticity of the earlier-generated vortices.

scholarly journals In silico investigation of biomechanical response of a human subjected to primary blast

2021 ◽  
Author(s):  
Sunil Sutar ◽  
Shailesh Ganpule
Keyword(s):  
White Matter ◽  
Blast Wave ◽  
Rotational Motion ◽  
Blast Waves ◽  
Primary Blast ◽  
Body Model ◽  
The Past ◽  
Biomechanical Response ◽  
The Brain ◽  
Full Body

The response of the brain to the explosion induced primary blast waves is actively sought. Over the past decade, reasonable progress has been made in the fundamental understanding of bTBI using head surrogates and animal models. Yet, the current understanding of how blast waves interact with the human is in nascent stages, primarily due to lack of data in humans. The biomechanical response in human is critically required so that connection to the aforementioned bTBI models can be faithfully established. Here, using a detailed, full-body human model, we elucidate the biomechanical cascade of the brain under a primary blast. The input to the model is incident overpressure as achieved by specifying charge mass and standoff distance through ConWep. The full-body model allows to holistically probe short- (<5 ms) and long-term (200 ms) brain biomechanical responses. The full-body model has been extensively validated against impact loading in the past. In this work, we validate the head model against blast loading. We also incorporate structural anisotropy of the brain white matter. Blast wave human interaction is modeled using a conventional weapon modeling approach. We demonstrate that the blast wave transmission, linear and rotational motion of the head are dominant pathways for the biomechanical loading of the brain, and these loading paradigms generate distinct biomechanical fields within the brain. Blast transmission and linear motion of the head govern the volumetric response, whereas the rotational motion of the head governs the deviatoric response. We also observe that blast induced head rotation alone produces a diffuse injury pattern in white matter fiber tracts. Lastly, we find that the biomechanical response under blast is comparable to the impact event. These insights will augment laboratory and clinical investigations of bTBI and help devise better blast mitigation strategies.

A new type of finite difference WENO schemes for Hamilton–Jacobi equations

2019 ◽  
Vol 30 (02n03) ◽  
pp. 1950020 ◽  
Author(s):  
Xiaohan Cheng ◽  
Jianhu Feng ◽  
Supei Zheng ◽  
Xueli Song
Keyword(s):  
Finite Difference ◽  
Weno Schemes ◽  
Numerical Examples ◽  
Weighted Essentially Nonoscillatory ◽  
New Type ◽  
Spurious Oscillations ◽  
Symmetry Requirement ◽  
Finite Difference Weno Schemes ◽  
Jacobi Equations ◽  
Fifth Order

In this paper, we propose a new type of finite difference weighted essentially nonoscillatory (WENO) schemes to approximate the viscosity solutions of the Hamilton–Jacobi equations. The new scheme has three properties: (1) the scheme is fifth-order accurate in smooth regions while keep sharp discontinuous transitions with no spurious oscillations near discontinuities; (2) the linear weights can be any positive numbers with the symmetry requirement and that their sum equals one; (3) the scheme can avoid the clipping of extrema. Extensive numerical examples are provided to demonstrate the accuracy and the robustness of the proposed scheme.

scholarly journals Diagonally Implicit Runge–Kutta Type Method for Directly Solving Special Fourth-Order Ordinary Differential Equations with Ill-Posed Problem of a Beam on Elastic Foundation

Algorithms ◽  
2018 ◽  
Vol 12 (1) ◽  
pp. 10 ◽  
Author(s):  
Nizam Ghawadri ◽  
Norazak Senu ◽  
Firas Adel Fawzi ◽  
Fudziah Ismail ◽  
Zarina Ibrahim
Keyword(s):  
Differential Equations ◽  
Ordinary Differential Equations ◽  
Elastic Foundation ◽  
Fourth Order ◽  
Sixth Order ◽  
Test Problems ◽  
Type Method ◽  
Ill Posed ◽  
Runge Kutta ◽  
Fifth Order

In this study, fifth-order and sixth-order diagonally implicit Runge–Kutta type (DIRKT) techniques for solving fourth-order ordinary differential equations (ODEs) are derived which are denoted as DIRKT5 and DIRKT6, respectively. The first method has three and the another one has four identical nonzero diagonal elements. A set of test problems are applied to validate the methods and numerical results showed that the proposed methods are more efficient in terms of accuracy and number of function evaluations compared to the existing implicit Runge–Kutta (RK) methods.

scholarly journals Fifth-Order Mapped Semi-Lagrangian Weighted Essentially Nonoscillatory Methods Near Certain Smooth Extrema

2014 ◽  
Vol 2014 ◽  
pp. 1-14 ◽  
Author(s):  
Lang Wu ◽  
Dazhi Zhang ◽  
Boying Wu ◽  
Xiong Meng
Keyword(s):  
Finite Difference ◽  
Finite Volume ◽  
Interpolation Scheme ◽  
Numerical Examples ◽  
Weighted Essentially Nonoscillatory ◽  
Accuracy Test ◽  
A Cell ◽  
Fifth Order ◽  
Cell Average ◽  
Essentially Nonoscillatory

Fifth-order mapped semi-Lagrangian weighted essentially nonoscillatory (WENO) methods at certain smooth extrema are developed in this study. The schemes contain the mapped semi-Lagrangian finite volume (M-SL-FV) WENO 5 method and the mapped compact semi-Lagrangian finite difference (M-C-SL-FD) WENO 5 method. The weights in the more common scheme lose accuracy at certain smooth extrema. We introduce mapped weighting to handle the problem. In general, a cell average is applied to construct the M-SL-FV WENO 5 reconstruction, and the M-C-SL-FD WENO 5 interpolation scheme is proposed based on an interpolation approach. An accuracy test and numerical examples are used to demonstrate that the two schemes reduce the loss of accuracy and improve the ability to capture discontinuities.

Blast Wave Mitigation from the Straight Tube by Using Water Part II - Numerical Simulation

2018 ◽  
Vol 910 ◽  
pp. 78-83 ◽  
Author(s):  
Yuta Sugiyama ◽  
Tomotaka Homae ◽  
Kunihiko Wakabayashi ◽  
Tomoharu Matsumura ◽  
Yoshio Nakayama
Keyword(s):  
Experimental Data ◽  
Numerical Simulation ◽  
Energy Transfer ◽  
Numerical Simulations ◽  
Blast Wave ◽  
Blast Waves ◽  
Straight Tube ◽  
Water Interface ◽  
Effect Of Water ◽  
Air Water Interface

This paper investigates explosions in a straight square tube in order to understand the mitigation effect of water on blast waves that emerge outside. Numerical simulations are used to assess the effect of water that is put inside the tube. The water reduces the peak overpressure outside, which agrees well with the experimental data. The increases in the kinetic and internal energies of the water are estimated, and the internal energy transfer at the air/water interface is shown to be an important factor in mitigating the blast wave in the present numerical method.

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