Turbulent mixing in high-altitude explosions

Conference · Tue Sep 01 04:00:00 EDT 1992

OSTI ID:7368504

Kuhl, A L; Bell, J B ^[1]; Ferguson, R E ^[2]; White, W W; McCartor, T H ^[3]

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1. Lawrence Livermore National Lab., CA (United States)
2. Naval Surface Warfare Center, Silver Spring, MD (United States)
3. Mission Research Corp., Nashua, NH (United States)

Numerical simulations of a high-altitude explosion were performed using a Godunov code with Adaptive Mesh Refinement (AMR). The code solves the two-dimensional (2-D), time-dependent conservation laws of inviscid gas dynamics while AMR is used to focus the computational effort in the mixing regions. The calculations revealed that a spherical density interface embedded in this flow was unstable and rolled up into a turbulent mixing layer. The shape of the interface was qualitatively similar to experimental photographs. Initially, the mixing layer width grew as a linear function of time, but eventually it reached an asymptotically-constant value. The flow field was azimuthally-averaged to evaluate the mean-flow profiles and the R.M.S. fluctuation profiles across the mixing layer. The mean kinetic energy rapidly approached zero as the blast wave decayed, but the fluctuating kinetic energy asymptotically approached a small constant value (a fraction of a percent of the maximum kinetic energy). This represents the rotational kinetic energy driven by the vorticity field, that continued to mix the fluid indefinitely. It was shown that the vorticity field corresponds to a function that fluctuates between plus and minus values -- with a volume-averaged mean of zero. The amplitude of the vorticity fluctuations decayed as t[sup [minus]1]. The corresponding enstrophy increased linearly with time because of a cascade process for the mean-squared vorticity. This result is in good agreement with the 2-D calculations of turbulent flow as reported by G.K. Batchelor. The problem should be recalculated in 3-D to study the decay of turbulent mixing for spherical interfaces.

• Research Organization: Lawrence Livermore National Lab., CA (United States)
• Sponsoring Organization: DOE; USDOE, Washington, DC (United States)
• DOE Contract Number: W-7405-ENG-48
• OSTI ID: 7368504
• Report Number(s): UCRL-JC-111818; CONF-9209377--1; ON: DE93017177
• Country of Publication: United States
• Language: English

Related Subjects

45 MILITARY TECHNOLOGY, WEAPONRY, AND NATIONAL DEFENSE
450100 -- Military Technology
Weaponry
& National Defense-- Chemical Explosions & Explosives
450200* -- Military Technology
Weaponry
& National Defense-- Nuclear Explosions & Explosives
A CODES
ATMOSPHERIC EXPLOSIONS
CHEMICAL EXPLOSIONS
COMPUTER CODES
COMPUTERIZED SIMULATION
CONSERVATION LAWS
DETONATION WAVES
EXPLOSIONS
FLUID FLOW
FLUID MECHANICS
MECHANICS
MIXING
NUCLEAR EXPLOSIONS
SHOCK WAVES
SIMULATION
TIME DEPENDENCE
TURBULENCE
TWO-DIMENSIONAL CALCULATIONS
VORTEX FLOW