Turbulent mixing in high-altitude explosions

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

OSTI ID:10172008

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 (US)
2. Naval Surface Warfare Center, Silver Spring, MD (US)
3. Mission Research Corp., Nashua, NH (US)

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: USDOE, Washington, DC (United States)
• DOE Contract Number: W-7405-ENG-48
• OSTI ID: 10172008
• Report Number(s): UCRL-JC-111818; CONF-9209377-1; ON: DE93017177; TRN: 93:002314
• Resource Relation: Conference: Symposium on atmospheric nuclear effects (SANE),Santa Barbara, CA (United States),14-18 Sep 1992; Other Information: PBD: Sep 1992
• Country of Publication: United States
• Language: English

Related Subjects

45 MILITARY TECHNOLOGY, WEAPONRY, AND NATIONAL DEFENSE
DETONATION WAVES
TURBULENCE
ATMOSPHERIC EXPLOSIONS
COMPUTERIZED SIMULATION
MIXING
CONSERVATION LAWS
SHOCK WAVES
NUCLEAR EXPLOSIONS
CHEMICAL EXPLOSIONS
VORTEX FLOW
A CODES
TWO-DIMENSIONAL CALCULATIONS
FLUID MECHANICS
TIME DEPENDENCE
450200
450100
NUCLEAR EXPLOSIONS AND EXPLOSIVES
CHEMICAL EXPLOSIONS AND EXPLOSIVES