Improvements in the Chart D Radiation-Hydrodynamic Code I: Analytic Equations of State.

Thompson, Starley L.

doi:10.2172/4125539

Cited by 219 publications

(276 citation statements)

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“…The early stage of an oblique impact (until transient cavity formation) is modeled with the three-dimensional code SOVA [Shuvalov, 1999] with simplified description of strength. Both codes are coupled with the ANEOS equation of state [Thompson and Lauson, 1972]. While shock wave decay in the target does not depend on the impact obliquity, deposition of high-velocity ejecta, responsible for secondary craters, differs substantially from a vertical impact.…”

Section: Numerical Modelsmentioning

confidence: 99%

Impact demagnetization of the Martian crust: Primaries versus secondaries

Artemieva

Hood

Ivanov

2005

Geophysical Research Letters

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[1] Numerical simulations presented here show that demagnetization of crust near the largest Martian basins by secondary impacts can be comparable to that by direct shock waves outside the transient cavity. The relative input from secondary impacts, which demagnetize only the uppermost layers, depends on the magnetic carrier distribution within the crust. Thus, we discuss properties of likely magnetic remanence carriers and their possible spatial distribution within the crust. Citation: Artemieva, N., Hood, and B. A. Ivanov (2005), Impact demagnetization of the Martian crust: Primaries versus secondaries, Geophys. Res. Lett., 32, L22204,

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Section: Numerical Modelsmentioning

confidence: 99%

Impact demagnetization of the Martian crust: Primaries versus secondaries

Artemieva

Hood

Ivanov

2005

Geophysical Research Letters

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“…CSQ is essentially a Eulerian code in which the material moves through a fixed mesh. The hydrocode makes use of the semianalytical equation of state ANEOS [Thompson and Lauson, 1972], a FORTRAN code designed tbr use with a number of hydrocodes [Thompson, 1990]. ANEOS uses the Helrnholtz free energy to construct thermodynamically consistent pressures, temperatures, and densities.…”

Section: Modelmentioning

confidence: 99%

Hydrocode simulation of the Chicxulub impact event and the production of climatically active gases

Pierazzo¹,

Kring²,

Melosh³

1998

J. Geophys. Res.

203

189

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Abstract. We constructed a numerical model of the Chicxulub impact event using the Chart-D Squared (CSQ) code coupled with the ANalytic Equation Of State (ANEOS) package. In the simulations we utilized a target stratigraphy based on borehole data and employed newly developed equations of state for the materials that are believed to play a crucial role in the impact-related extinction hypothesis: carbonates (calcite) and evaporites (anhydrite). Simulations explored the effects of different projectile sizes (10 to 30 km in diameter) and porosity (0 to 50%). The effect of impact speed is addressed by doing simulations of asteroid impacts (v•=20 km/s) and comet impacts (¾i=50 km/s). The masses of climatically important species injected into the upper atmosphere by the impact increase with the energy of the impact event, ranging from 3 50 to 3 500 Gt for CO2, from 40 to 560 Gt for S, and from 200 to 1400 Gt for water vapor. While our results are in good agreement with those of Ivanov et al. [1996], our estimated CO2 production is 1 to 2 orders of magnitude lower than the results of Takata and Ahrens [1994], indicating that the impact event enhanced the end-Cretaceous atmospheric CO2 inventory by, at most, 40%. Consequently, sulfur may have been the most important climatically active gas injected into the stratosphere. The amount of S released by the impact is several orders of magnitude higher than any known volcanic eruption and, with H20, is high enough to produce a sudden and significant perturbation of Earth's climate.

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“…Equations (3)- (5) must be supplemented by an EOS, which in this study was provided by lookup tables derived from the CHARTD database. 58 The CHARTD EOS is thermodynamically consistent and employs a Thomas-Fermi-Dirac approximation 59 for the plasma electrons and a DebyeGr€ uneisen model for the ions. The treatment of ionization is based on a Saha description 60 with modifications to account for pressure ionization effects.…”

Section: The Numerical Modelmentioning

confidence: 99%

Numerical simulations of the ablative Rayleigh-Taylor instability in planar inertial-confinement-fusion targets using the FastRad3D code

et al. 2016

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The ablative Rayleigh-Taylor (RT) instability is a central issue in the performance of laser-accelerated inertial-confinement-fusion targets. Historically, the accurate numerical simulation of this instability has been a challenging task for many radiation hydrodynamics codes, particularly when it comes to capturing the ablatively stabilized region of the linear dispersion spectrum and modeling ab initio perturbations. Here, we present recent results from two-dimensional numerical simulations of the ablative RT instability in planar laser-ablated foils that were performed using the Eulerian code FastRad3D. Our study considers polystyrene, (cryogenic) deuterium-tritium, and beryllium target materials, quarter- and third-micron laser light, and low and high laser intensities. An initial single-mode surface perturbation is modeled in our simulations as a small modulation to the target mass density and the ablative RT growth-rate is calculated from the time history of areal-mass variations once the target reaches a steady-state acceleration. By performing a sequence of such simulations with different perturbation wavelengths, we generate a discrete dispersion spectrum for each of our examples and find that in all cases the linear RT growth-rate γ is well described by an expression of the form γ=α [kg/(1+ϵ kLm)]1/2−βkVa, where k is the perturbation wavenumber, g is the acceleration of the target, Lm is the minimum density scale-length, Va is the ablation velocity, and ϵ is either one or zero. The dimensionless coefficients α and β in the above formula depend on the particular target and laser parameters and are determined from two-dimensional simulation results through the use of a nonlinear curve-fitting procedure. While our findings are generally consistent with those of Betti et al. (Phys. Plasmas 5, 1446 (1998)), the ablative RT growth-rates predicted in this investigation are somewhat smaller than the values previously reported for the same target and laser parameters. It is speculated that differences in the equation-of-state and opacity models are largely responsible for the discrepancy. Resolution of this issue awaits the development of better experimental diagnostics capable of measuring small-wavelength (5–20 μm) perturbation growth due to the ablative RT instability in the linear regime.

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Improvements in the Chart D Radiation-Hydrodynamic Code I: Analytic Equations of State.

Cited by 219 publications

References 0 publications

Impact demagnetization of the Martian crust: Primaries versus secondaries

Impact demagnetization of the Martian crust: Primaries versus secondaries

Hydrocode simulation of the Chicxulub impact event and the production of climatically active gases

Numerical simulations of the ablative Rayleigh-Taylor instability in planar inertial-confinement-fusion targets using the FastRad3D code

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