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Title: Observation and analysis of emergent coherent structures in a high-energy-density shock-driven planar mixing layer experiment

Abstract

Coherent emergent structures have been observed in a high-energy-density supersonic mixing layer experiment. A millimeter-scale shock tube uses lasers to drive Mbar shocks into the tube volume. The shocks are driven into initially solid foam (60 mg/cm 3) hemicylinders separated by an Al or Ti metal tracer strip; the components are vaporized by the drive. Before the experiment disassembles, the shocks cross at the tube center, creating a very fast (ΔU > 200 km/s) shear-unstable zone. After several nanoseconds, an expanding mixing layer is measured, and after 10+ ns we observe the appearance of streamwise-periodic, spanwise-aligned rollers associated with the primary Kelvin-Helmholtz instability of mixing layers. We additionally image roller pairing and spanwise-periodic streamwise-aligned filaments associated with secondary instabilities. New closures are derived to connect length scales of these structures to estimates of fluctuating velocity data otherwise unobtainable in the high-energy-density environment. Finally, this analysis indicates shear-induced specific turbulent energies 10 3 – 10 4 times higher than the nearest conventional experiments. Because of difficulties in continuously driving systems under these conditions and the harshness of the experimental environment limiting the usable diagnostics, clear evidence of these developing structures has never before been observed in this regime.

Authors:
ORCiD logo [1]; ORCiD logo [1]; ORCiD logo [1]
  1. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Publication Date:
Research Org.:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1402602
Alternate Identifier(s):
OSTI ID: 1295979
Report Number(s):
LA-UR-16-20044
Journal ID: ISSN 2470-0045; PLEEE8; TRN: US1703240
Grant/Contract Number:  
AC52-06NA25396; AC52-07NA27344
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Physical Review E
Additional Journal Information:
Journal Volume: 94; Journal Issue: 2; Journal ID: ISSN 2470-0045
Publisher:
American Physical Society (APS)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS

Citation Formats

Doss, Forrest William, Flippo, Kirk Adler, and Merritt, Elizabeth Catherine. Observation and analysis of emergent coherent structures in a high-energy-density shock-driven planar mixing layer experiment. United States: N. p., 2016. Web. doi:10.1103/PhysRevE.94.023101.
Doss, Forrest William, Flippo, Kirk Adler, & Merritt, Elizabeth Catherine. Observation and analysis of emergent coherent structures in a high-energy-density shock-driven planar mixing layer experiment. United States. doi:10.1103/PhysRevE.94.023101.
Doss, Forrest William, Flippo, Kirk Adler, and Merritt, Elizabeth Catherine. Wed . "Observation and analysis of emergent coherent structures in a high-energy-density shock-driven planar mixing layer experiment". United States. doi:10.1103/PhysRevE.94.023101. https://www.osti.gov/servlets/purl/1402602.
@article{osti_1402602,
title = {Observation and analysis of emergent coherent structures in a high-energy-density shock-driven planar mixing layer experiment},
author = {Doss, Forrest William and Flippo, Kirk Adler and Merritt, Elizabeth Catherine},
abstractNote = {Coherent emergent structures have been observed in a high-energy-density supersonic mixing layer experiment. A millimeter-scale shock tube uses lasers to drive Mbar shocks into the tube volume. The shocks are driven into initially solid foam (60 mg/cm3) hemicylinders separated by an Al or Ti metal tracer strip; the components are vaporized by the drive. Before the experiment disassembles, the shocks cross at the tube center, creating a very fast (ΔU > 200 km/s) shear-unstable zone. After several nanoseconds, an expanding mixing layer is measured, and after 10+ ns we observe the appearance of streamwise-periodic, spanwise-aligned rollers associated with the primary Kelvin-Helmholtz instability of mixing layers. We additionally image roller pairing and spanwise-periodic streamwise-aligned filaments associated with secondary instabilities. New closures are derived to connect length scales of these structures to estimates of fluctuating velocity data otherwise unobtainable in the high-energy-density environment. Finally, this analysis indicates shear-induced specific turbulent energies 103 – 104 times higher than the nearest conventional experiments. Because of difficulties in continuously driving systems under these conditions and the harshness of the experimental environment limiting the usable diagnostics, clear evidence of these developing structures has never before been observed in this regime.},
doi = {10.1103/PhysRevE.94.023101},
journal = {Physical Review E},
number = 2,
volume = 94,
place = {United States},
year = {Wed Aug 03 00:00:00 EDT 2016},
month = {Wed Aug 03 00:00:00 EDT 2016}
}

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