Atomic scale mixing for inertial confinement fusion associated hydro instabilities

Melvin, Jeremy; Rao, P. Krishna; Kaufman, R. N.; Lim, Hyunkyung; Yu, Yan; Glimm, James; Sharp, David H.

doi:10.1016/j.hedp.2013.01.007

Cited by 7 publications

(13 citation statements)

References 19 publications

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“…Our previous work addressed convergence issues for probability density functions (PDF) and their indefinite integrals, the cumulative distribution functions (CDF) [21,22] with experimental validation in [20,23,24], relative to the hot-cold water splitter experiments [16]. We have also considered two-point statistical descriptions of RT and RM mixtures [25][26][27].…”

Section: A Transportmentioning

confidence: 99%

Mixing with applications to inertial-confinement-fusion implosions

et al. 2017

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Approximate 1D as well as 2D and 3D simulations are playing an important supporting role in the design and analysis of future experiments at NIF. This paper is mainly concerned with 1D simulations, used extensively in design and optimization. We couple a 1D buoyancy-drag mix model for the mixing zone edges with a 1D Inertial Confinement Fusion (ICF) simulation code. This analysis predicts that National Ignition Campaign designs are located close to a performance cliff, so that modeling errors, design features (fill tube and tent) and additional, unmodeled instabilities could lead to significant levels of mix. The performance cliff we identify is associated with multimode plastic ablator (CH) mix into the hot spot Deuterium and Tritium (DT). The buoyancy-drag mix model is mode number independent, and selects implicitly a range of maximum growth modes.Our main conclusion is that single effect instabilities are predicted not to lead to hot spot mix, while combined mode mixing effects are predicted to affect hot spot thermodynamics and possibly hot spot mix. Combined with the stagnation Rayleigh-Taylor instability, we find the potential for mix effects in combination with the ice to gas DT boundary, numerical effects of Eulerian species CH concentration diffusion and ablation driven instabilities.With the help of a convenient package of plasma transport parameters developed here, we give an approximate determination of these quantities in the regime relevant to the NIC experiments, while ruling out a variety of mix possibilities. Plasma transport parameters affect the 1D buoyancy-drag mix model primarily through its phenomenological drag coefficient as well as the 1D hydro model the buoyancy-drag equation is coupled to.

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Section: A Transportmentioning

confidence: 99%

Mixing with applications to inertial-confinement-fusion implosions

et al. 2017

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“…This also agrees with the spectra reported by previous papers. 24,25 However, it is clear from the noise in these figures that the current sample size (64 slices) does not give sufficient statistics at the low wavenumber end of the spectrum to make conclusive statements about the exact slope of the inverse spectrum. Even in recent DNS of homogeneous 2D turbulence, a resolution of 16 000þ points in each direction has been required to clearly see both cascades in stationary turbulence, hence it would be somewhat optimistic to expect a clear result here.…”

Section: E Turbulent Kinetic Energy Spectramentioning

confidence: 94%

“…Two recent papers focussing on turbulent transport and mesh convergence in 2D RM in cylindrical geometry highlight the different physics expected in 2D inhomogeneous mixing. 24,25 The assumption that the two-dimensional problem is simpler and easier to run than the 3D case at first appears quite clear. However, the physics of two-dimensional turbulence is dramatically different from it's 3D counterpart, as is very well summarised in the review by Kraichnan and Montgomery 26 and more recently by Boffetta and Ecke.…”

Section: Introductionmentioning

confidence: 99%

Numerical simulations of the two-dimensional multimode Richtmyer-Meshkov instability

Thornber

Zhou

2015

Physics of Plasmas

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The two-dimensional Richtmyer-Meshkov instability occurs as shock waves pass through a perturbed material interface, triggering transition to an inhomogeneous turbulence variable density flow. This paper presents a series of large-eddy-simulations of the two dimensional turbulent RM instability and compares the results to the fully three dimensional simulations. There are two aims for this paper, the first is to explore what numerical resolution is required for a statistically converged solution for a two dimensional inhomogeneous flow field. The second aim is to elucidate the key differences in flow physics between the two dimensional and three dimensional RichtmyerMeshkov instabilities, particularly their asymptotic self-similar regime. Convergence is achieved using 64 independent realisations and grid resolutions up to 4096 2 in the plane. It is shown that for narrowband cases the growth rate h ¼ 0.48 which is substantially higher than the three-dimensional equivalent. Mix measures are consistently lower compared to three-dimensional, and the kinetic energy distribution is homogeneous at late time. The broadband case has a similar initial growth rate as the three-dimensional case, with a marginally lower h ¼ 0.63. Mix is similar in magnitude, but is reducing at late time. The spectra in both cases exhibit the dual-cascade expected from twodimensional turbulence. V C 2015 AIP Publishing LLC. [http://dx.

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“…However, for turbulence modeling, the analogous resolution of ambiguity requires specifying the turbulent transport, exactly the quantity which introduces the ambiguity. Nonuniqueness of apparently converged LES is observed in practice and is an issue that solution verification methodology has yet to address [29].…”

Section: Examples Of Nonuniqueness For Equations Of Evolution Mathemmentioning

confidence: 99%

Large eddy simulation, turbulent transport and the renormalization group

Glimm

Plohr

Lim

et al. 2016

Annals of Mathematical Sciences and Applications

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In large eddy simulations, the Reynolds averages of nonlinear terms are not directly computable in terms of the resolved variables and require a closure hypothesis or model, known as a subgrid scale term. Inspired by the renormalization group (RNG), we introduce an expansion for the unclosed terms, carried out explicitly to all orders. In leading order, this expansion defines subgrid scale unclosed terms, which we relate to the dynamic subgrid scale closure models. The expansion, which generalizes the Leonard stress for closure analysis, suggests a systematic higher order determination of the model coefficients.The RNG point of view sheds light on the nonuniqueness of the infinite Reynolds number limit. For the mixing of N species, we see an N + 1 parameter family of infinite Reynolds number solutions labeled by dimensionless parameters of the limiting Euler equations, in a manner intrinsic to the RNG itself. Large eddy simulations, with their Leonard stress and dynamic subgrid models, break this nonuniqueness and predict unique model coefficients on the basis of theory. In this sense large eddy simulations go beyond the RNG methodology, which does not in general predict model coefficients.

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Atomic scale mixing for inertial confinement fusion associated hydro instabilities

Cited by 7 publications

References 19 publications

Mixing with applications to inertial-confinement-fusion implosions

Mixing with applications to inertial-confinement-fusion implosions

Numerical simulations of the two-dimensional multimode Richtmyer-Meshkov instability

Large eddy simulation, turbulent transport and the renormalization group

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