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Title: Off-center blast in a shocked medium

Abstract

When multiple blasts occur at different times, the situation arises in which a blast wave is propagating into a medium that has already been shocked. Determining the evolution in shape of the second shock is not trivial, as it is propagating into air that is not only non-uniform, but also non-stationary. To accomplish this task, we employ the method of Kompaneets to determine the shape of a shock in a non-uniform media. We also draw from the work of Korycansky [1] on an off-center explosion in a medium with radially varying density. Extending this to treat non-stationary flow, and making use of approximations to the Sedov solution for the point blast problem, we are able to determine an analytic expression for the evolving shape of the second shock. Specifically, we consider the case of a shock in air at standard ambient temperature and pressure, with the second shock occurring shortly after the original blast wave reaches it, as in a sympathetic detonation.

Authors:
 [1];  [1]
  1. New Mexico Tech., Socorro, NM (United States)
Publication Date:
Research Org.:
Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
Sponsoring Org.:
USDOE National Nuclear Security Administration (NNSA)
OSTI Identifier:
1411607
Alternate Identifier(s):
OSTI ID: 1333807; OSTI ID: 1411601
Report Number(s):
SAND-2016-8212J; SAND-2017-3197J; SAND-2017-6941J
Journal ID: ISSN 0938-1287; 646842
Grant/Contract Number:
AC04-94AL85000
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Shock Waves
Additional Journal Information:
Journal Name: Shock Waves; Journal ID: ISSN 0938-1287
Publisher:
Springer
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; blast waves; Kompaneets equation; Korycansky solution; multiple burst; shock front; 97 MATHEMATICS AND COMPUTING; kompaneets equation; korycansky solution

Citation Formats

Duncan-Miller, Gabrielle Christiane, and Stone, William D. Off-center blast in a shocked medium. United States: N. p., 2017. Web. doi:10.1007/s00193-017-0747-3.
Duncan-Miller, Gabrielle Christiane, & Stone, William D. Off-center blast in a shocked medium. United States. doi:10.1007/s00193-017-0747-3.
Duncan-Miller, Gabrielle Christiane, and Stone, William D. Thu . "Off-center blast in a shocked medium". United States. doi:10.1007/s00193-017-0747-3.
@article{osti_1411607,
title = {Off-center blast in a shocked medium},
author = {Duncan-Miller, Gabrielle Christiane and Stone, William D.},
abstractNote = {When multiple blasts occur at different times, the situation arises in which a blast wave is propagating into a medium that has already been shocked. Determining the evolution in shape of the second shock is not trivial, as it is propagating into air that is not only non-uniform, but also non-stationary. To accomplish this task, we employ the method of Kompaneets to determine the shape of a shock in a non-uniform media. We also draw from the work of Korycansky [1] on an off-center explosion in a medium with radially varying density. Extending this to treat non-stationary flow, and making use of approximations to the Sedov solution for the point blast problem, we are able to determine an analytic expression for the evolving shape of the second shock. Specifically, we consider the case of a shock in air at standard ambient temperature and pressure, with the second shock occurring shortly after the original blast wave reaches it, as in a sympathetic detonation.},
doi = {10.1007/s00193-017-0747-3},
journal = {Shock Waves},
number = ,
volume = ,
place = {United States},
year = {Thu Nov 16 00:00:00 EST 2017},
month = {Thu Nov 16 00:00:00 EST 2017}
}

Journal Article:
Free Publicly Available Full Text
This content will become publicly available on November 16, 2018
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  • When multiple blasts occur at different times, the situation arises in which a blast wave is propagating into a medium that has already been shocked. Determining the evolution in shape of the second shock is not trivial, as it is propagating into air that is not only non-uniform, but also non-stationary. To accomplish this task, we employ the method of Kompaneets to determine the shape of a shock in a non-uniform media. We also draw from the work of Korycansky [1] on an off-center explosion in a medium with radially varying density. Extending this to treat non-stationary flow, and makingmore » use of approximations to the Sedov solution for the point blast problem, we are able to determine an analytic expression for the evolving shape of the second shock. Specifically, we consider the case of a shock in air at standard ambient temperature and pressure, with the second shock occurring shortly after the original blast wave reaches it, as in a sympathetic detonation.« less
  • Abstract not provided.
  • Based on the recently accumulated observational facts on the radio features in the Galactic center, a shocked-jet model is proposed for the radio bridge that connects Sgr A and the radio arc. The bridge is interpreted as a tilted magnetized jet filled with a supersonic and shocked gas ejected from the Galactic nucleus. The jet is largely bent when it encounters an ambient poloidal magnetic field. A magnetic bow shock is formed ahead of the jet at the interaction surface with the ambient magnetic field and is observed as the radio arc. An internal shock wave occurring in the jetmore » is observed as a jump in the gas density on the radio bridge. 16 references.« less
  • The Stephan's Quintet (hereafter SQ) is a template source to study the impact of galaxies interaction on the physical state and energetics of their gas. We report on IRAM single-dish CO observations of the SQ compact group of galaxies. These observations follow up the Spitzer discovery of bright mid-IR H{sub 2} rotational line emission (L(H{sub 2}) Almost-Equal-To 10{sup 35} W) from warm (10{sup 2-3} K) molecular gas, associated with a 30 kpc long shock between a galaxy, NGC 7318b, and NGC 7319's tidal arm. We detect CO(1-0), (2-1) and (3-2) line emission in the inter-galactic medium (IGM) with complex profiles,more » spanning a velocity range of Almost-Equal-To 1000 km s{sup -1}. The spectra exhibit the pre-shock recession velocities of the two colliding gas systems (5700 and 6700 km s{sup -1}), but also intermediate velocities. This shows that much of the molecular gas has formed out of diffuse gas accelerated by the galaxy-tidal arm collision. CO emission is also detected in a bridge feature that connects the shock to the Seyfert member of the group, NGC 7319, and in the northern star forming region, SQ-A, where a new velocity component is identified at 6900 km s{sup -1}, in addition to the two velocity components already known. Assuming a Galactic CO(1-0) emission to H{sub 2} mass conversion factor, a total H{sub 2} mass of Almost-Equal-To 5 Multiplication-Sign 10{sup 9} M{sub Sun} is detected in the shock. The ratio between the warm H{sub 2} mass derived from Spitzer spectroscopy, and the H{sub 2} mass derived from CO fluxes is Almost-Equal-To 0.3 in the IGM of SQ, which is 10--100 times higher than in star-forming galaxies. The molecular gas carries a large fraction of the gas kinetic energy involved in the collision, meaning that this energy has not been thermalized yet. The kinetic energy of the H{sub 2} gas derived from CO observations is comparable to that of the warm H{sub 2} gas from Spitzer spectroscopy, and a factor Almost-Equal-To 5 greater than the thermal energy of the hot plasma heated by the collision. In the shock and bridge regions, the ratio of the PAH-to-CO surface luminosities, commonly used to measure the star formation efficiency of the H{sub 2} gas, is lower (up to a factor 75) than the observed values in star-forming galaxies. We suggest that turbulence fed by the galaxy-tidal arm collision maintains a high heating rate within the H{sub 2} gas. This interpretation implies that the velocity dispersion on the scale of giant molecular clouds in SQ is one order of magnitude larger than the Galactic value. The high amplitude of turbulence may explain why this gas is not forming stars efficiently.« less
  • We present observations of fine-structure line emission of atomic sulfur, iron, and rotational lines of molecular hydrogen in shocks associated with several Class 0 protostars obtained with the Infrared Spectrograph of the Spitzer Space Telescope. We use these observations to investigate the 'missing sulfur problem', that significantly less sulfur is found in dense regions of the interstellar medium (ISM) than in diffuse regions. For sources where the sulfur fine-structure line emission is co-spatial with the detected molecular hydrogen emission and in the presence of weak iron emission, we derive sulfur and H{sub 2} column densities for the associated molecule-dominated C-shocks.more » We find the S I abundance to be ≳5%-10% of the cosmic sulfur abundance, indicating that atomic sulfur is a major reservoir of sulfur in shocked gas. This result suggests that in the quiescent dense ISM sulfur is present in some form that is released from grains as atoms, perhaps via sputtering, within the shock.« less