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Title: Mixing transition in a shocked variable-density flow

Abstract

We measure two-dimensional velocity and density fluctuations in a shock-driven heavy gas curtain for three different incident Mach numbers (M = 1.21, 1.36, and 1.50) and a fixed initial perturbation. We study the time evolution of the velocity and density fields and observe two different mixing transitions in this unsteady flow. The first transition is caused by small-scale mixing in vortex cores, while the second transition is related to increased homogenization across the mixing layer and a drive towards isotropy. By measuring the anisotropy of the velocity fluctuations and the evolution of the turbulent kinetic energy, we are able to assess the anisotropy of the flow. For the first time in Richtmyer-Meshkov (RM) flows, we measure and compare turbulent length scales derived from both the density and velocity field measurements, and we find ratios of Liepmann-Taylor to inner-viscous scales (λ Lv) that are inconsistent with those found using Reynolds number scaling based on circulation, Re Γ, or based on turbulent kinetic energy, Re K. At late times, Re K better reflects the decay of the mixing field than Reynolds numbers that are based upon mixing width or circulation. We also estimate the time evolution of dissipation and Kolmogorov scalesmore » for the first time in RM flows. When we estimate the Taylor microscale (λ T) for our experiments using both density and velocity, the density microscale agrees well with with the relationship λ T = √10δRe- 1/2 where Re = ReK and δ is the mixing layer width, but the velocity-based Taylor microscale follows a new scaling of λ T = 10δRe -1/2.« less

Authors:
 [1];  [2];  [3]; ORCiD logo [1]
  1. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
  2. Indian Inst. of Technology (IIT), Mumbai (India)
  3. Univ. of New Mexico, Albuquerque, NM (United States)
Publication Date:
Research Org.:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1492592
Report Number(s):
LA-UR-15-22836
Journal ID: ISSN 1070-6631; PHFLE6
Grant/Contract Number:  
89233218CNA000001
Resource Type:
Accepted Manuscript
Journal Name:
Physics of Fluids
Additional Journal Information:
Journal Volume: 27; Journal Issue: 11; Journal ID: ISSN 1070-6631
Publisher:
American Institute of Physics (AIP)
Country of Publication:
United States
Language:
English
Subject:
42 ENGINEERING; Richtmyer-Meshkov; mixing; turbulence

Citation Formats

Orlicz, G. C., Balasubramanian, Sridhar, Vorobieff, P., and Prestridge, K. P. Mixing transition in a shocked variable-density flow. United States: N. p., 2015. Web. doi:10.1063/1.4935183.
Orlicz, G. C., Balasubramanian, Sridhar, Vorobieff, P., & Prestridge, K. P. Mixing transition in a shocked variable-density flow. United States. doi:10.1063/1.4935183.
Orlicz, G. C., Balasubramanian, Sridhar, Vorobieff, P., and Prestridge, K. P. Mon . "Mixing transition in a shocked variable-density flow". United States. doi:10.1063/1.4935183. https://www.osti.gov/servlets/purl/1492592.
@article{osti_1492592,
title = {Mixing transition in a shocked variable-density flow},
author = {Orlicz, G. C. and Balasubramanian, Sridhar and Vorobieff, P. and Prestridge, K. P.},
abstractNote = {We measure two-dimensional velocity and density fluctuations in a shock-driven heavy gas curtain for three different incident Mach numbers (M = 1.21, 1.36, and 1.50) and a fixed initial perturbation. We study the time evolution of the velocity and density fields and observe two different mixing transitions in this unsteady flow. The first transition is caused by small-scale mixing in vortex cores, while the second transition is related to increased homogenization across the mixing layer and a drive towards isotropy. By measuring the anisotropy of the velocity fluctuations and the evolution of the turbulent kinetic energy, we are able to assess the anisotropy of the flow. For the first time in Richtmyer-Meshkov (RM) flows, we measure and compare turbulent length scales derived from both the density and velocity field measurements, and we find ratios of Liepmann-Taylor to inner-viscous scales (λL/λv) that are inconsistent with those found using Reynolds number scaling based on circulation, ReΓ, or based on turbulent kinetic energy, ReK. At late times, ReK better reflects the decay of the mixing field than Reynolds numbers that are based upon mixing width or circulation. We also estimate the time evolution of dissipation and Kolmogorov scales for the first time in RM flows. When we estimate the Taylor microscale (λT) for our experiments using both density and velocity, the density microscale agrees well with with the relationship λT = √10δRe-1/2 where Re = ReK and δ is the mixing layer width, but the velocity-based Taylor microscale follows a new scaling of λT = 10δRe-1/2.},
doi = {10.1063/1.4935183},
journal = {Physics of Fluids},
number = 11,
volume = 27,
place = {United States},
year = {2015},
month = {11}
}

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