Investigation of two‐dimensional numerical shock propagation using a weighted essentially non‐oscillatory scheme

2005 ◽  
Vol 118 (3) ◽  
pp. 2008-2008
Author(s):  
Mark S. Wochner ◽  
Anthony A. Atchley

A numerical scheme for shock propagation in three space dimensions is presented. The motion of the leading shock surface is calculated by using Whitham’s theory of geometrical shock dynamics. The numerical scheme is used to examine the focusing of initially curved shock surfaces and the diffraction of shocks in a pipe with a 90° bend. Numerical and experimental results for the corresponding two-dimensional or axi-symmetrical cases are used to compare with the new and more complicated three-dimensional results.


2017 ◽  
Vol 828 ◽  
pp. 104-134 ◽  
Author(s):  
Brandon Lieberthal ◽  
D. Scott Stewart ◽  
Alberto Hernández

Taylor blast wave (TBW) theory and geometrical shock dynamics (GSD) theory describe a radially expanding shock wave front through an inert material, typically an ideal gas, in the strong blast wave limit and weak acoustic limit respectively. We simulate a radially expanding blast shock in air using a hydrodynamic simulation code and numerically describe the intermediate region between these two limits. We test our description of the intermediate shock phase through a two-dimensional simulation of the Bryson and Gross experiment. We then apply the principles of GSD to materials that follow the Mie–Gruneisen equation of state, such as plastics and metals, and derive an equation that accurately relates the acceleration, velocity and curvature of the shock through these materials. Along with detonation shock dynamics (DSD), which describes detonation shock propagation through high explosive fluids, we develop a hybrid DSD/GSD model for the simulation of heterogeneous explosives. This model enables computationally efficient simulation of the shock front in high explosive/inert mixtures consisting of simple or complex geometric configurations. We simulate an infinite two-dimensional slab consisting of one half explosive, PBXN-9, and one half aluminium and model the boundary angle conditions using shock polar analysis. We also simulate a series of high explosive unit cells embedded with aluminium spherical particles, and we compare the propagation of the detonation shock front with a direct numerical simulation performed with the ALE3D code.


2011 ◽  
Vol 7 (S279) ◽  
pp. 397-398 ◽  
Author(s):  
Yudai Suwa

AbstractWe present two-dimensional numerical simulations of core-collapse supernova including multi-energy neutrino radiative transfer. We aim to examine the influence of the equation of state (EOS) for the dense nuclear matter. We employ four sets of EOSs, namely, those by Lattimer and Swesty (LS) and Shen et al., which became standard EOSs in the core-collapse supernova community. We reconfirm that not every EOS produces an explosion in spherical symmetry, which is consistent with previous works. In two-dimensional simulations, we find that the structure of the accretion flow is significantly different between LS EOS and Shen EOS, inducing an even qualitatively different evolution of the shock wave, namely, the LS EOS leads to shock propagation beyond 2000 km from the center, while the Shen EOS shows only oscillations within 500 km. The possible origins of the difference are discussed.


1996 ◽  
Vol 327 ◽  
pp. 161-197 ◽  
Author(s):  
N. K.-R. Kevlahan

A new theory of the propagation of weak shocks into non-uniform, two-dimensional flows is introduced. The theory is based on a description of shock propagation in terms of a manifold equation together with compatibility conditions for shock strength and its normal derivatives behind the shock. This approach was developed by Ravindran & Prasad (1993) for shocks of arbitrary strength propagating into a medium at rest and is extended here to non-uniform media and restricted to moderately weak shocks. The theory is tested against known analytical solutions for cylindrical and plane shocks, and against a full direct numerical simulation (DNS) of a shock propagating into a sinusoidal shear flow. The test against DNS shows that the present theory accurately predicts the evolution of a moderately weak shock front, including the formation of shock-shocks due to shock focusing. The theory is then applied to the focusing of an initially parabolic shock, and to the propagation of an initially straight shock into a variety of simple flows (sinusoidal shear, vortex array, point-vortex array) exhibiting some fundamental properties of turbulent flows. A number of relations are deduced for the variation of shock quantities with initial shock strength MS0 and the Mach number of the flow ahead of the shock MU (e.g. separation of shock-shocks and maximum shock strength at a focus). It is found that shock-shocks are likely to form in turbulent flows with Mt/M1N > 0.14–0.25, where Mt is the average Mach number of the turbulence and M1N is the Mach number of the shock in a flow at rest. The shock moves up to 1.5% faster in a two-dimensional vortex array than in uniform flow.


1966 ◽  
Vol 24 ◽  
pp. 118-119
Author(s):  
Th. Schmidt-Kaler

I should like to give you a very condensed progress report on some spectrophotometric measurements of objective-prism spectra made in collaboration with H. Leicher at Bonn. The procedure used is almost completely automatic. The measurements are made with the help of a semi-automatic fully digitized registering microphotometer constructed by Hög-Hamburg. The reductions are carried out with the aid of a number of interconnected programmes written for the computer IBM 7090, beginning with the output of the photometer in the form of punched cards and ending with the printing-out of the final two-dimensional classifications.


1966 ◽  
Vol 24 ◽  
pp. 3-5
Author(s):  
W. W. Morgan

1. The definition of “normal” stars in spectral classification changes with time; at the time of the publication of theYerkes Spectral Atlasthe term “normal” was applied to stars whose spectra could be fitted smoothly into a two-dimensional array. Thus, at that time, weak-lined spectra (RR Lyrae and HD 140283) would have been considered peculiar. At the present time we would tend to classify such spectra as “normal”—in a more complicated classification scheme which would have a parameter varying with metallic-line intensity within a specific spectral subdivision.


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