Simulation and flow physics of a shocked and reshocked high-energy-density mixing layer

Direct numerical simulations of a three-dimensional cylindrical Richtmyer–Meshkov instability with and without chemical reactions are carried out to explore the chemical reaction effects on the statistical characteristics of transition and turbulent mixing. We adopt 9-species and 19-reaction models of non-premixed hydrogen and oxygen separated by a multimode perturbed cylindrical interface. A new definition of mixing width suitable for a chemical reaction is introduced, and we investigate the spatio-temporal evolution of typical flow parameters within the mixing regions. After reshock with a fuller mixing of fuels and oxygen, the chemical reaction becomes sufficiently apparent at affecting the evolution of the flow fields. Because of the generation of a combustion wave within the combustion regions and propagation, the growth of the mixing width with a chemical reaction is accelerated, especially around the outer radius with large temperature gradient profiles. However, the viscous dissipation rate in the early stage of the chemical reaction is greater because of heat release, which results in weakened turbulent mixing within the mixing regions. We confirm that small-scale structures begin to develop after reshock and then decay over time. During the developing process, helicity also begins to develop, in addition to kinetic energy, viscous dissipation rate, enstrophy, etc. In the present numerical simulations with cylindrical geometry, the fluctuating flow fields evolve from quasi-two-dimensional perturbations, and the generations of helicity can capture this transition process. The weakened fluctuations during shock compression can be explained as the inverse energy cascade, and the chemical reaction can promote this inverse energy cascade process.

show abstract

“…2020; Bender et al. 2021). Because of the appearance of nitrogen, we need to deal with the case of three-species mixing.…”

Section: Resultsmentioning

confidence: 99%

“…The mixed mass can be regarded as a direct marker of the mixing regions, which is very important for experimental measurements (Zhou, Cabot & Thornber 2016;Zhang et al 2020;Zhou et al 2020;Bender et al 2021). Because of the appearance of nitrogen, we need to deal with the case of three-species mixing.…”

Section: Mixed Massmentioning

confidence: 99%

Effect of chemical reaction on mixing transition and turbulent statistics of cylindrical Richtmyer–Meshkov instability

Yan

Wang

et al. 2022

J. Fluid Mech.

View full text Add to dashboard Cite

show abstract

“…Ares is a massively parallel, multi-dimensional, multi-physics simulation code [12]. Its capabilities include Arbitrary Lagrangian-Eulerian (ALE) hydrodynamics with Adaptive Mesh Refinement (AMR), radiation diffusion and transport, 3T plasma physics and high explosive modeling.…”

Section: Aresmentioning

confidence: 99%

Understanding Power and Energy Utilization in Large Scale Production Physics Simulation Codes

Ryujin¹,

Vargas²,

Karlin³

et al. 2022

Preprint

View full text Add to dashboard Cite

Power is an often-cited reason for moving to advanced architectures on the path to Exascale computing. This is due to the practical concern of delivering enough power to successfully site and operate these machines, as well as concerns over energy usage while running large simulations. Since accurate power measurements can be difficult to obtain, processor thermal design power (TDP) is a possible surrogate due to its simplicity and availability. However, TDP is not indicative of typical power usage while running simulations. Using commodity and advance technology systems at Lawrence Livermore National Laboratory (LLNL) and Sandia National Laboratory, we performed a series of experiments to measure power and energy usage in running simulation codes. These experiments indicate that large scale LLNL simulation codes are significantly more efficient than a simple processor TDP model might suggest.

show abstract

“…These results in asymmetric errors. Some other methods exist [32,59] but they could not be employed in the present experiments.…”

Section: Error On the Interface Positionmentioning

confidence: 99%

“…Furthermore, a precise control and knowledge of the initial conditions remains challenging for any RTI experiments [29,30]. High Energy Density (HED) settings allow to circumvent these intrinsic limitations [31,32].…”

Section: Introductionmentioning

confidence: 99%

Exploring the Atwood-number dependence of the highly nonlinear Rayleigh-Taylor instability regime in high-energy-density conditions

et al. 2021

View full text Add to dashboard Cite

We experimentally study the late time, highly nonlinear regime of the Rayleigh-Taylor Instability in a decelerating phase. A series of laser-driven experiments is performed on the LULI2000 laser, in which the initial Atwood number is varied by adjusting the decelerating medium density. The high power laser is used in a direct drive configuration to put into motion a solid target. Its rear side, which initially possesses a two-dimensional machined sinusoidal perturbations, expands and decelerates into a foam leading to a Rayleigh-Taylor unstable situation. The interface position and morphology are measured by time-resolved x-ray radiography. We develop a simple Atwood dependent model describing the motion of the decelerating interface, from which its acceleration history is obtained. The measured amplitude of the instability, or mixing zone width, is then compared with late time acceleration dependent Rayleigh-Taylor instability models. The shortcoming of this classical models, when applied to high energy density conditions, is shown. This calls into question their uses for systems, where a shock wave is present, such as those found in laboratory astrophysics or in Inertial Confinement Fusion.

show abstract

Simulation and flow physics of a shocked and reshocked high-energy-density mixing layer

Abstract: Abstract

Cited by 32 publications

References 130 publications

Effect of chemical reaction on mixing transition and turbulent statistics of cylindrical Richtmyer–Meshkov instability

Effect of chemical reaction on mixing transition and turbulent statistics of cylindrical Richtmyer–Meshkov instability

Understanding Power and Energy Utilization in Large Scale Production Physics Simulation Codes

Exploring the Atwood-number dependence of the highly nonlinear Rayleigh-Taylor instability regime in high-energy-density conditions

Contact Info

Product

Resources

About