Bulletin of the American Physical Society
15th APS Topical Conference on Shock Compression of Condensed Matter
Volume 52, Number 8
Sunday–Friday, June 24–29, 2007; Kohala Coast, Hawaii
Session D5: Hydrodynamic and Applied Modeling |
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Chair: John Maw, AWE, UK Room: Fairmont Orchid Hotel Plaza III |
Monday, June 25, 2007 3:45PM - 4:00PM |
D5.00001: Numerical Study of Underwater Explosions and Following Bubble Pulses Atsushi Abe, Masahide Katayama, Kenji Murata, Yukio Kato, Katsumi Tanaka Underwater explosions and following bubble pulses were simulated by using the hydrocode AUTODYN. The pressure gradient depended on the water depth was applied to the water, and the effects of the atmospheric pressure and the gravity on the bubble properties were investigated numerically. In the deep and shallow water depth cases the bubble properties or pressure histories obtained numerically were compared with the empirical formula or the experimental data. Not only the pressure gradient in the water and the atmospheric pressure but also the application of the JWL EOS to slow energy release of the non-ideal explosive (Miller model) were found to be of great importance to simulate the generation of the bubble pulse precisely. Although the gravitational term during the dynamic analysis can be neglected in numerical analyses for very short time phenomena, it is indispensable to simulate the buoyancy of the bubble because the time range of the bubble behavior is some hundred times longer than that of the explosion phenomena. [Preview Abstract] |
Monday, June 25, 2007 4:00PM - 4:15PM |
D5.00002: Dynamic Response of Submerged Solids to Extreme Fluid Loading Shi Wei Gong, Ming Cheng, Zhuangjian Liu, Chun Lu This paper deals with the dynamic response of submerged solids to extreme fluid loading induced by underwater explosion. The computational procedure is elaborated for the simulation of charge detonation, shock wave propagation from water media to the target solid, fluid-solid interaction, and dynamic response of the submerged solid. The benchmark tests are conducted, showing that the present method is reasonable and feasible. Cases studies are carried out for a single solid exposed to a single charge detonation or multiple charge detonations; and also multiple solids exposed to a single charge detonation or multiple charge detonations. The effects of different solid geometries on their dynamic responses to underwater explosive loading are also examined. From the results obtained, some insights to the problem of submerged solids subjected to underwater explosive loading are deduced. [Preview Abstract] |
Monday, June 25, 2007 4:15PM - 4:30PM |
D5.00003: Modeling of Non-Eroding Penetration Using ALE3D and Zapotec James Cazamias, Stephen Schraml Accurate predictions of non-eroding penetration are becoming of increasing importance to the Army. Sandia's Zapotec (a coupling of Pronto and CTH) has been the code of choice, but there has been some concerns expressed about relying on a single methodology. Consequently, LLNL's ALE3D (which uses a slide line based approach) is currently being investigated for insertion into ARL programs. While simulations of concrete targets would be preferred for comparison purposes, the current state of concrete models precludes this. As a benchmark, we choose to model the penetration experiments of steel projectiles against aluminum targets (Piekutowski, A.J., et al., Int. J. Impact Engng 23 723-734 (1999)) to examine the differences between the two methodologies. [Preview Abstract] |
Monday, June 25, 2007 4:30PM - 4:45PM |
D5.00004: Numerical Modeling of Munroe Jets Charles Mader, Michael Gittings Munroe jets are formed by the oblique interaction of detonation products from two explosive charges separated by an air gap. The jet consists of a high velocity jet of low density precursor gases and particles that travel faster than the primary jet which is a high pressure regular shock reflection. The Los Alamos PHERMEX Data Volumes [1] contain 40 radiographs taken by Douglas Venable in the 1960's of Munroe Jets generated by Composition B explosive charges separated by 5 to 80 mm of air. In several of the experiments the Munroe jets interacted with thin Tantalum foils and with aluminum plates. The PHERMEX experiments were modeled using the AMR Eulerian reactive hydrodynamic code, NOBEL [2,3], When the detonation arrives at the bottom of the gap, the detonation product s expand against the air and precursor gases travel at high velocity ahead of the detonation wave in the explosive. The expanding detonation products from the explosive collide and result in a high pressure regular shock reflection.. Interaction with a metal plate consists of first the interaction of the precursor gases and then the high pressure regular shock reflection arrives to further damage the metal plate. \newline [1] Los Alamos PHERMEX Data, Volumes I, II, and III, UC Press 1980. \newline [2] Numerical Modeling of Water Waves, Second Edition, Charles L. Mader, CRC Press 2004 \newline [3] Numerical Modeling of Explosions and Propellants, Charles L. Mader, CRC Press 1998. [Preview Abstract] |
Monday, June 25, 2007 4:45PM - 5:00PM |
D5.00005: Verification Test Problems Bill Moran We present analytic solutions to two test problems that can be used to check the hydrodynamic implementation in computer codes designed to calculate the propagation of shocks in spherically convergent geometry. Our analysis is restricted to fluid materials with constant bulk modulus. In the first problem we present the exact initial acceleration and pressure gradient at the outer surface of a sphere subjected to an exponentially decaying pressure of the form $P(t)=P_0 e^{-\alpha t}$. We show that very-finely-zoned hydro-code simulations are in excellent agreement with our analytic solution. In the second problem we discuss the implosions of incompressible and compressible spherical shells. For the incompressible case, we present the velocity time-history at the inner and outer surfaces of the shell and the radial pressure profile across the shell thickness. We also present a semi-analytic solution to the time-evolution of a nearly spherical shell with arbitrary but small initial 3-dimensional (3-D) perturbations on its inner and outer surfaces. We show that 3-D hydro-code calculations converge to the semi-analytic solution as the resolution increases in the hydro-code. For the compressible case we present the initial conditions that lead to a shock-less acceleration and a time evolution very similar to the incompressible case. [Preview Abstract] |
Monday, June 25, 2007 5:00PM - 5:15PM |
D5.00006: ABSTRACT WITHDRAWN |
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