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Journal articles on the topic 'Hydrodynamics instabilities'

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Author: Grafiati

Published: 10 December 2022

Last updated: 29 January 2023

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1

Stevens, Ian R. "Colliding stellar winds: X-ray emission and instabilities." Symposium - International Astronomical Union 163 (1995): 486–94. http://dx.doi.org/10.1017/s0074180900202519.

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Colliding stellar winds are an important part of early-type binaries. In this paper I discuss the phenomenon, concentrating mainly on the basic hydrodynamics of colliding winds, and the physics of X-ray emission. The following topics are covered:1) Basic physics: The basic characteristics of the shock-produced thermal X-ray emission, and discuss general trends of X-ray emission from colliding wind binaries (CWBs).2) Hydrodynamic simulations: Recent calculations have found that the interface in colliding winds is usually dynamically unstable, with three distinct instabilities.3) Gamma Velorum: recent ROSAT observations give much insight into colliding winds. I discuss recent hydrodynamic calculations pertaining to these observations.4) Radiation Hydrodynamics in CWBs: Recent calculations have included the effects of both radiation fields on the wind hydrodynamics in colliding wind systems.

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2

Proctor, M. R. E. "Hydrodynamics and nonlinear instabilities." European Journal of Mechanics - B/Fluids 18, no. 3 (May 1999): 562–63. http://dx.doi.org/10.1016/s0997-7546(99)90013-4.

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3

Arnett, David. "Theory, observation and experiment: stellar hydrodynamics." Symposium - International Astronomical Union 189 (1997): 389–94. http://dx.doi.org/10.1017/s0074180900116936.

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Computer technology now allows two dimensional (2D) simulations, with complex microphysics, of stellar hydrodynamics and evolutionary sequences, and holds the promise for 3D. Careful validation of astrophysical methods, by laboratory experiment, by critical comparison of numerical and analytical methods, and by observation are necessary for the development of simulation methods with reliable predictive capability. Recent and surprising results from isotopic patterns in pre-solar grains, 2D hydrodynamic simulations of stellar evolution, and laser tests and computer simulations of Richtmeyer-Meshkov and Rayleigh-Taylor instabilities will be discussed, and related to stellar evolution and supernovae.

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4

Valcke, S., S. De Rijcke, E. Rödiger, and H. Dejonghe. "Kelvin-Helmholtz instabilities in smoothed particle hydrodynamics." Monthly Notices of the Royal Astronomical Society 408, no. 1 (July 15, 2010): 71–86. http://dx.doi.org/10.1111/j.1365-2966.2010.17127.x.

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5

Valcke, S., S. De Rijcke, and E. Röediger. "Kelvin-Helmholtz Instabilities in Smoothed Particle Hydrodynamics." EAS Publications Series 48 (2011): 405–6. http://dx.doi.org/10.1051/eas/1148088.

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6

Jackson, David P., Raymond E. Goldstein, and Andrejs O. Cebers. "Hydrodynamics of fingering instabilities in dipolar fluids." Physical Review E 50, no. 1 (July 1, 1994): 298–307. http://dx.doi.org/10.1103/physreve.50.298.

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7

WOOD-VASEY, W. M., K. S. BUDIL, B. A. REMINGTON, S. G. GLENDINNING, A. M. RUBENCHIK, M. BERNING, J. O. KANE, and J. T. LARSEN. "Computational modeling of classical and ablative Rayleigh–Taylor instabilities." Laser and Particle Beams 18, no. 4 (October 2000): 583–93. http://dx.doi.org/10.1017/s0263034600184022.

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Modeling plus simulations using the one-dimensional Lagrangian radiation-hydrodynamics code HYADES are compared with data from classical and ablative Rayleigh–Taylor experiments conducted on the Nova laser. Comparisons between the experiments and modeling for both the gross hydrodynamic motion and the perturbation evolution are made and show good agreement. A third order perturbation analysis is applied to demonstrate the onset of nonlinearity. A simple, physically intuitive saturation model is used to describe the growth further into the nonlinear regime. Finally, we present the first comparison of the Betti ablation front theory with indirect-drive RT data and obtain good agreement.

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8

Llamoza, Johan, and Desiderio A. Vasquez. "Structures and Instabilities in Reaction Fronts Separating Fluids of Different Densities." Mathematical and Computational Applications 24, no. 2 (May 17, 2019): 51. http://dx.doi.org/10.3390/mca24020051.

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Density gradients across reaction fronts propagating vertically can lead to Rayleigh–Taylor instabilities. Reaction fronts can also become unstable due to diffusive instabilities, regardless the presence of a mass density gradient. In this paper, we study the interaction between density driven convection and fronts with diffusive instabilities. We focus in fluids confined in Hele–Shaw cells or porous media, with the hydrodynamics modeled by Brinkman’s equation. The time evolution of the front is described with a Kuramoto–Sivashinsky (KS) equation coupled to the fluid velocity. A linear stability analysis shows a transition to convection that depends on the density differences between reacted and unreacted fluids. A stabilizing density gradient can surpress the effects of diffusive instabilities. The two-dimensional numerical solutions of the nonlinear equations show an increase of speed due to convection. Brinkman’s equation lead to the same results as Darcy’s laws for narrow gap Hele–Shaw cells. For large gaps, modeling the hydrodynamics using Stokes’ flow lead to the same results.

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9

Ramaswamy, Sriram, and Madan Rao. "Active-filament hydrodynamics: instabilities, boundary conditions and rheology." New Journal of Physics 9, no. 11 (November 30, 2007): 423. http://dx.doi.org/10.1088/1367-2630/9/11/423.

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10

Cha, Seung-Hoon, Shu-Ichiro Inutsuka, and Sergei Nayakshin. "Kelvin-Helmholtz instabilities with Godunov smoothed particle hydrodynamics." Monthly Notices of the Royal Astronomical Society 403, no. 3 (April 11, 2010): 1165–74. http://dx.doi.org/10.1111/j.1365-2966.2010.16200.x.

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11

Benney, D. J., and K. Chow. "An Alternative Approach to Nonlinear Instabilities in Hydrodynamics." Studies in Applied Mathematics 73, no. 3 (December 1985): 261–67. http://dx.doi.org/10.1002/sapm1985733261.

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12

Balbus, Steven A., and John F. Hawley. "Instability, Turbulence, and Enhanced Transport in Accretion Disks." International Astronomical Union Colloquium 163 (1997): 90–100. http://dx.doi.org/10.1017/s0252921100042536.

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AbstractThe nature of MHD and hydrodynamical turbulence in accretion disks is discussed. Comparison is made with planar Couette flow, a classical system prone to nonlinear shear instability resulting in enhanced turbulent transport. Both Keplerian and non-Keplerian hydrodynamical disks are studied, and it is found that only constant angular momentum disks are unstable to nonlinear disturbances and develop enhanced turbulent transport. Convective instabilities do not lead to enhanced turbulent transport. Hydrodynamical Keplerian disks are quite stable to nonlinear disturbances. Several lines of argument are presented which all lead to this conclusion, but the key to disk turbulence is the interaction between the stress tensor and the mean flow gradients. The nature of this coupling is found to determine completely the stability properties of disks (hydrodynamics and magnetic), and the nature of turbulent transport. The weak field MHD instability, which is of great astrophysical importance, displays the same type of stress tensor – mean flow coupling that all classical local shear instabilities exhibit. Hydrodynamical Keplerian disks, on the other hand, do not. Accretion disk turbulence is MHD turbulence.

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13

Vanegas, Juan M., David Peterson, Taras I. Lakoba, and Valeri N. Kotov. "Spinodal de-wetting of light liquids on graphene." Journal of Physics: Condensed Matter 34, no. 17 (February 25, 2022): 175001. http://dx.doi.org/10.1088/1361-648x/ac4f7e.

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Abstract We demonstrate theoretically the possibility of spinodal de-wetting in heterostructures made of light–atom liquids (hydrogen, helium, and nitrogen) deposited on suspended graphene. Extending our theory of film growth on two-dimensional (2D) materials to include analysis of surface instabilities via the hydrodynamic Cahn–Hilliard-type equation, we characterize in detail the spatial and temporal scales of the resulting spinodal de-wetting patterns. Both linear stability analysis and direct numerical simulations of the surface hydrodynamics show micron-sized (generally material dependent) patterns of ‘dry’ regions. The physical reason for the development of such instabilities on graphene can be traced back to the inherently weak van der Waals interactions between atomically thin materials and atoms in the liquid. Thus 2D materials could represent a new theoretical and technological platform for studies of spinodal de-wetting.

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14

Morris, Joseph Peter. "A Study of the Stability Properties of Smooth Particle Hydrodynamics." Publications of the Astronomical Society of Australia 13, no. 1 (January 1996): 97–102. http://dx.doi.org/10.1017/s1323358000020610.

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AbstractWhen using a formulation of smooth particle hydrodynamics (SPH) which conserves momentum exactly the motion of the particles is observed to be unstable to negative stress. It is also found that under normal circumstances a lattice of SPH particles is potentially unstable to transverse waves. This paper is a summary of a detailed report (Morris 1994) investigating the nature of these and other instabilities in depth. Approaches which may be used to eliminate these instabilities are suggested. It is found that the stability properties of SPH in general improve as higher-order spline interpolants, approximating a Gaussian, are used as kernels.

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15

Zalesak, Steven T., Andrew J. Schmitt, A. L. Velikovich, and J. H. Gardner. "Modeling fluid instabilities in inertial confinement fusion hydrodynamics codes." Physics of Plasmas 12, no. 5 (May 2005): 056311. http://dx.doi.org/10.1063/1.1885004.

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16

Moiseev, S. S., and R. Z. Sagdeev. "Problems of secondary instabilities in hydrodynamics and in plasma." Radiophysics and Quantum Electronics 29, no. 9 (September 1986): 808–12. http://dx.doi.org/10.1007/bf01034478.

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17

Schmitt, Andrew J., and Stephen P. Obenschain. "The importance of laser wavelength for driving inertial confinement fusion targets. II. Target design." Physics of Plasmas 30, no. 1 (January 2023): 012702. http://dx.doi.org/10.1063/5.0118093.

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We describe details of radiation-hydrodynamics simulations of directly driven targets for inertial confinement fusion using laser drivers with different laser wavelengths. Of particular interest here are comparisons of frequency-tripled glass (laser wavelength 351 nm) lasers with the argon fluoride (193 nm) and krypton fluoride (248 nm) excimer lasers and the effects that these laser wavelengths have on the target designs. We explore the effect these drivers have on the compromise involved between lowering laser plasma instabilities (LPIs) or hydrodynamic instabilities while providing high gains and seek to quantify this trade-off. Short-wavelength drivers have significant advantages, primarily in using less power and energy to drive targets. Additionally, they expand the allowed operating regime that is constrained by LPI avoidance and the production of higher pressures needed for more hydrodynamically stable targets. Potential disadvantages to shorter drive wavelengths, such as increased imprint, are examined and found to be unimportant.

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18

Owocki, Stanley P. "Instabilities in massive stars." Symposium - International Astronomical Union 212 (2003): 281–90. http://dx.doi.org/10.1017/s0074180900212345.

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A defining property of massive stars is the dominant, dynamical role played by radiation throughout the stellar interior, atmosphere, and wind. Associated with this radiation hydrodynamics are several distinct kinds of instabilities that can lead to convection in both core and envelope, clumping in atmosphere and wind outflow, and perhaps even the dramatic mass loss outbursts associated with Luminous Blue Variable phases. Here I review these instabilities with emphasis on basic physical properties of radiative driving. I draw on two specific examples of dynamical instability, namely the strong instability associated with line-driving of a stellar wind outflow, and the global stellar instabilities associated with approaching or exceeding a modified Eddington limit. I conclude with a brief mention of recent ideas on the role of stellar rotation in the shaping of bipolar LBV outbursts.

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Junk, Veronika, Fabian Heitsch, and Thorsten Naab. "The Kelvin-Helmholtz Instability in Smoothed-Particle Hydrodynamics." Proceedings of the International Astronomical Union 2, S235 (August 2006): 210. http://dx.doi.org/10.1017/s1743921306006168.

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AbstractSmoothed Particle Hydrodynamics (SPH) simulations are a powerful tool to investigate hydrodynamical processes in astrophysics such as the formation of galactic disks. Dense gas clouds raining on the forming disk are possibly disrupted by Kelvin-Helmholtz-Instabilities (KHI). To understand the evolution of the halo clouds, we have to ascertain the capability of SPH to treat the KHI correctly, since SPH-methods tend to suffer from an innate surface tension and viscosity effects, both of which could dampen the KHI. We analytically derive a growth rate of the KHI including surface tension and viscosity in the linear regime, and compare this growth rate to results of numerical simulations by an SPH method and a grid-based method. We find that SPH in some cases suppresses the KHI (Junk et al., in prep).

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20

Knobloch, Edgar, Alex Mahalov, and Jerrold E. Marsden. "Normal forms for three-dimensional parametric instabilities in ideal hydrodynamics." Physica D: Nonlinear Phenomena 73, no. 1-2 (May 1994): 49–81. http://dx.doi.org/10.1016/0167-2789(94)90225-9.

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21

Casner, A. "Recent progress in quantifying hydrodynamics instabilities and turbulence in inertial confinement fusion and high-energy-density experiments." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 379, no. 2189 (December 7, 2020): 20200021. http://dx.doi.org/10.1098/rsta.2020.0021.

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Since the seminal paper of Nuckolls triggering the quest of inertial confinement fusion (ICF) with lasers, hydrodynamic instabilities have been recognized as one of the principal hurdles towards ignition. This remains true nowadays for both main approaches (indirect drive and direct drive), despite the advent of MJ scale lasers with tremendous technological capabilities. From a fundamental science perspective, these gigantic laser facilities enable also the possibility to create dense plasma flows evolving towards turbulence, being magnetized or not. We review the state of the art of nonlinear hydrodynamics and turbulent experiments, simulations and theory in ICF and high-energy-density plasmas and draw perspectives towards in-depth understanding and control of these fascinating phenomena. This article is part of a discussion meeting issue ‘Prospects for high gain inertial fusion energy (part 2)’.

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22

Guzik, Joyce A., Arthur N. Cox, Kate M. Despain, and Michael S. Soukup. "Pulsation Hydrodynamics of Luminous Blue Variables and Pulsation-Driven Winds." International Astronomical Union Colloquium 169 (1999): 337–44. http://dx.doi.org/10.1017/s0252921100072213.

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AbstractMany physical factors, including radial and nonradial pulsation, rotation, radiation pressure, convection, magnetic fields, or dynamical instabilities may play important roles in the hydrodynamics of Luminous Blue Variables. We review the current status of hydrodynamic modeling of LBV envelopes, and describe results of our models using the one-dimensional nonlinear hydrodynamics code of Ostlie and Cox. We find that the models pulsate in several simultaneous radial modes, driven by the helium and Fe ionization к effect. The pulsations have quasi-periods between 5 and 80 days, with radial velocity amplitudes of 50-200 km/sec, and may be identified with the LBV microvariations. In some cases, depending on luminosity-to-mass ratio and helium abundance, deep layers in the model can periodically exceed the Eddington luminosity limit. The key to exceeding LE is the inclusion of the time dependence of convection: Near the regions of opacity peaks produced by Fe and helium ionization, convection is turning on and off during each pulsation cycle. If convection cannot turn on rapidly enough to transport the required luminosity through the region, the Eddington limit is exceeded. If this region of the star is sufficiently adiabatic, an “outburst” may occur. In the hydrodynamic models, an outburst is indicated by the photospheric radial velocity suddenly becoming very large, and the photospheric radius increasing monotonically over several pulsation cycles. Such pulsation-triggered outbursts may be responsible for the driving of variable, nonspherical winds. If large and infrequent enough, these outbursts may be identified with the classic LBV eruptions accompanied by episodic mass loss.

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23

GYULASSY, MIKLOS. "FROM QED SPARKS TO QCD LIGHTNING: (OR HOW I SURVIVED W. GREINER'S 70TH BIRTHDAY PARTY)." International Journal of Modern Physics E 16, no. 03 (April 2007): 787–803. http://dx.doi.org/10.1142/s0218301307006289.

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In celebration of Walter Greiner's 70th birthday and half century of physics, I discuss some of our collaborative work starting with nonlinear vacuum polarization in over-critical QED, early attempts to justify nuclear hydrodynamics via two-stream pionic instabilities, frustrations with the imperfect hadronic world, and recent works pondering the "perfect fluidity" of the sQGP discovered at RHIC.

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24

Mathews, William G. "Radiation Hydrodynamics of the Broad Line Region in Seyfert Galaxies and Quasars." International Astronomical Union Colloquium 89 (1986): 346–68. http://dx.doi.org/10.1017/s0252921100086164.

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The broad line region in quasars and in the nuclei of active galaxies is the site of remarkable hydrodynamic activity unprecedented elsewhere in the universe. Considerable theoretical effort has been directed to determine how this intense radiation is related to high velocity gas motions in these small regions, which, because of their great distances, cannot be resolved by direct observation. A better theoretical understanding of the nature of the broad line-emitting gas involves many novel aspects of radiation hydrodynamics and may eventually provide insights into the nature of the mysterious quasar phenomenon itself.Continuum and emission line properties of active galaxies and quasars are sufficiently similar that there is little doubt that both can be accounted for by a similar or closely related physical model. The main difference is one of luminosity; typical quasars are considerably brighter than Seyfert galaxies.In the discussion below the relevant observations of quasars and active galaxies are briefly reviewed with an emphasis on the physical properties of the line-emitting gas and its immediate environment. Arguments that support the importance of radiation forces in producing the observed gas velocities are summarized. Finally, the nature of the acceleration process is described with particular attention paid to the various instabilities that may be present and which are generally characteristic of situations in which plasma velocities result directly from the deposition of radiative momentum. In fact, these troublesome instabilities suggest that radiative forces, although very strong, may provide only a partial explanation of the gasdynamical activity observed.

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25

Zubkov, P. I. "MHD Instabilities in the dynamic model of plasma open switches." Laser and Particle Beams 15, no. 1 (March 1997): 45–51. http://dx.doi.org/10.1017/s0263034600010739.

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The dynamic model of plasma open switches is proposed in this article. It is based on the initiation and development of force instabilities (pinches and necks) in spatially inhomogeneous plasma accelerated by the magnetic field pressure. The model proposed does not require the consideration of subtle effects at the pinch implosion stage. It allows one to account for main features of the operation of plasma current open switches within the framework of magnetic hydrodynamics. It also provides quantitative estimates in good agreement with experimental results.

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Desai, Karna M., Thomas Y. Steiman-Cameron, Scott Michael, Kai Cai, and Richard H. Durisen. "A 3D hydrodynamics study of gravitational instabilities in a young circumbinary disc." Monthly Notices of the Royal Astronomical Society 483, no. 2 (November 30, 2018): 2347–61. http://dx.doi.org/10.1093/mnras/sty3240.

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27

Ganzenmüller, G. C., M. Sauer, M. May, and S. Hiermaier. "Hourglass control for Smooth Particle Hydrodynamics removes tensile and rank-deficiency instabilities." European Physical Journal Special Topics 225, no. 2 (March 14, 2016): 385–95. http://dx.doi.org/10.1140/epjst/e2016-02631-x.

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28

Barber, Jacqueline, Khellil Sefiane, David Brutin, and Lounes Tadrist. "Hydrodynamics and heat transfer during flow boiling instabilities in a single microchannel." Applied Thermal Engineering 29, no. 7 (May 2009): 1299–308. http://dx.doi.org/10.1016/j.applthermaleng.2008.07.004.

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29

Rowther, Sahl, Rebecca Nealon, and Farzana Meru. "Warping Away Gravitational Instabilities in Protoplanetary Discs." Astrophysical Journal 925, no. 2 (February 1, 2022): 163. http://dx.doi.org/10.3847/1538-4357/ac3975.

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Abstract We perform three-dimensional smoothed-particle hydrodynamics simulations of warped, non-coplanar gravitationally unstable discs to show that as the warp propagates through the self-gravitating disk, it heats up the disk rendering it gravitationally stable, thus losing their spiral structure and appearing completely axisymmetric. In their youth, protoplanetary discs are expected to be massive and self-gravitating, which results in nonaxisymmetric spiral structures. However recent observations of young protoplanetary discs with the Atacama Large Millimeter/submillimeter Array have revealed that discs with large-scale spiral structure are rarely observed in the midplane. Instead, axisymmetric discs, with some also having ring and gap structures, are more commonly observed. Our work invloving warps, non-coplanar disk structures that are expected to commonly occur in young discs, potentially resolves this discrepancy between observations and theoretical predictions. We demonstrate that they are able to suppress the large-scale spiral structure of self-gravitating protoplanetary discs.

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Roycroft, R., J. P. Sauppe, and P. A. Bradley. "Double cylinder target design for study of hydrodynamic instabilities in multi-shell ICF." Physics of Plasmas 29, no. 3 (March 2022): 032704. http://dx.doi.org/10.1063/5.0083190.

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Cylindrical implosions are used to study hydrodynamic instability growth for inertial confinement fusion (ICF) applications, as the cylindrical geometry allows for easier diagnostic access while retaining convergence effects. In this work, we use the established cylindrical implosion platform [Palaniyappan et al., Phys. Plasmas 27, 042708 (2020)] to inform the double shell ICF campaign [Montgomery et al., Phys. Plasmas 25, 092706 (2018)]. We present a design for a double cylindrical target as an analogue to the double shell ICF capsule in order to study hydrodynamic instability growth on the high-Z inner shell. Our design work is done with two-dimensional (2D) Eulerian radiation-hydrodynamics simulations, considering the axial uniformity of the implosion and feasibility of measuring the instability growth of pre-seeded single mode sinusoidal perturbations. We discuss in depth the design for a target to be directly driven at the OMEGA laser facility [Boehly et al., Opt. Commun. 133, 495 (1997)]. We evaluate the design for axial implosion symmetry and visibility of instability growth using synthetic radiographs constructed from the simulations, as the instability growth on the inner cylinder is experimentally measured using x-ray radiography of the implosion. We find that the seeded perturbation growth on the inner cylinder should be visible in an experiment, even with axial implosion asymmetry and preheat. We compare our 2D simulations with linear theory predictions for perturbation growth and show that a cylinder with lower azimuthal mode number (mode-20) perturbations compares more favorably with linear theory, while a cylinder with higher azimuthal mode number (mode-40) perturbations at the same starting amplitude saturates and is over-predicted by linear theory.

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Liu, Hauyu Baobab, Michihiro Takami, Tomoyuki Kudo, Jun Hashimoto, Ruobing Dong, Eduard I. Vorobyov, Tae-Soo Pyo, et al. "Circumstellar disks of the most vigorously accreting young stars." Science Advances 2, no. 2 (February 2016): e1500875. http://dx.doi.org/10.1126/sciadv.1500875.

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Stars may not accumulate their mass steadily, as was previously thought, but in a series of violent events manifesting themselves as sharp stellar brightening. These events can be caused by fragmentation due to gravitational instabilities in massive gaseous disks surrounding young stars, followed by migration of dense gaseous clumps onto the star. Our high-resolution near-infrared imaging has verified the presence of the key associated features, large-scale arms and arcs surrounding four young stellar objects undergoing luminous outbursts. Our hydrodynamics simulations and radiative transfer models show that these observed structures can indeed be explained by strong gravitational instabilities occurring at the beginning of the disk formation phase. The effect of those tempestuous episodes of disk evolution on star and planet formation remains to be understood.

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WEBB, G. M., A. ZAKHARIAN, and G. P. ZANK. "Wave mixing and instabilities in cosmic-ray-modified shocks and flows." Journal of Plasma Physics 61, no. 4 (May 1999): 553–99. http://dx.doi.org/10.1017/s0022377898007466.

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Wave mixing equations describing the interaction of short-wavelength sound waves and entropy waves in two-fluid cosmic ray hydrodynamics in a non-uniform, large-scale, background flow in one Cartesian space dimension are investigated. The wave interaction coefficients depend on large-scale gradients in the background flow, and consist of two physically distinct components. The first component consists of wave-damping terms due to the diffusing cosmic rays, plus squeezing instability terms associated with the large-scale cosmic ray pressure gradient. These effects were first investigated by Drury and Dorfi in a study of the propagation of short-wavelength WKB sound waves in cosmic-ray-modified flows and shocks. The second component describes gas dynamical wave mixing effects due to gradients of the gas entropy S and the gas dynamical Riemann invariants (R±) of the background flow. A Green function solution is used to illustrate the coupling of the backward and forward sound waves for the case of a uniform background flow, in which the coupling coefficients depend on the parameter α = a2c/2κ, where ac is the cosmic-ray ‘sound speed’ and κ is the hydrodynamical cosmic-ray diffusion coefficient. Analytical WKB approximation methods and numerical simulations are used to investigate the modifications of the cosmic ray squeezing instability by wave mixing in cosmic-ray-modified shocks and pressure balance structures. Astrophysical applications to instabilities in supernova remnant shocks are discussed.

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33

Sukumaran, Sreejith, and G. S. Ranganath. "Hydrodynamics of smectic-Cliquid crystals: Field and flow induced instabilities in confined geometries." Physical Review E 57, no. 5 (May 1, 1998): 5597–608. http://dx.doi.org/10.1103/physreve.57.5597.

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Goyal, Rahul, and Bhupendra K. Gandhi. "Review of hydrodynamics instabilities in Francis turbine during off-design and transient operations." Renewable Energy 116 (February 2018): 697–709. http://dx.doi.org/10.1016/j.renene.2017.10.012.

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35

Garcia-Perciante, A. L., L. S. Garcia-Colin, and Alfredo Sandoval-Villalbazo. "On the nature of the so-called generic instabilities in dissipative relativistic hydrodynamics." General Relativity and Gravitation 41, no. 7 (December 14, 2008): 1645–54. http://dx.doi.org/10.1007/s10714-008-0735-0.

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36

ANDREEV, P. A., and L. S. KUZ'MENKOV. "WAVES OF MAGNETIC MOMENT AND GENERATION OF WAVES BY NEUTRON BEAM IN QUANTUM MAGNETIZED PLASMA." International Journal of Modern Physics B 26, no. 32 (December 11, 2012): 1250186. http://dx.doi.org/10.1142/s021797921250186x.

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This paper is devoted to studying of dispersion of waves in the magnetized plasma with the spin and exploring of new methods of the generation wave in the plasma. We consider the dispersion of waves, existed in the plasma in consequence of dynamic of the magnetic moments. It is shown there are nine new waves in the magnetized plasma because of the magnetic moments dynamic. We show there are instabilities at propagation of the neutron beam through the plasma. Increments of instabilities caused by neutron beam are calculated. For studying of this effects we generalize and use the method of the many-particle quantum hydrodynamics. Described processes can play important role at calculation of the stability and the safeness of the nuclear reactors and the studying of the processes in the atmosphere of the neutron stars.

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ROSU, H. C., and R. LÓPEZ-SANDOVAL. "BAROTROPIC FRW COSMOLOGIES WITH A DIRAC-LIKE PARAMETER." Modern Physics Letters A 19, no. 20 (June 28, 2004): 1529–35. http://dx.doi.org/10.1142/s0217732304013763.

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Using the known connection between Schrödinger-like equations and Dirac-like equations in the supersymmetric context, we discuss an extension of FRW barotropic cosmologies in which a Dirac mass-like parameter is introduced. New Hubble cosmological parameters HK(η) depending on the Dirac-like parameter are plotted and compared with the standard Hubble case H0(η). The new HK(η) are complex quantities. The imaginary part is a supersymmetric way of introducing dissipation and instabilities in the barotropic FRW hydrodynamics.

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Paddock, R. W., H. Martin, R. T. Ruskov, R. H. H. Scott, W. Garbett, B. M. Haines, A. B. Zylstra, et al. "One-dimensional hydrodynamic simulations of low convergence ratio direct-drive inertial confinement fusion implosions." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 379, no. 2189 (December 7, 2020): 20200224. http://dx.doi.org/10.1098/rsta.2020.0224.

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Indirect drive inertial confinement fusion experiments with convergence ratios below 17 have been previously shown to be less susceptible to Rayleigh–Taylor hydrodynamic instabilities, making this regime highly interesting for fusion science. Additional limitations imposed on the implosion velocity, in-flight aspect ratio and applied laser power aim to further reduce instability growth, resulting in a new regime where performance can be well represented by one-dimensional (1D) hydrodynamic simulations. A simulation campaign was performed using the 1D radiation-hydrodynamics code HYADES to investigate the performance that could be achieved using direct-drive implosions of liquid layer capsules, over a range of relevant energies. Results include potential gains of 0.19 on LMJ-scale systems and 0.75 on NIF-scale systems, and a reactor-level gain of 54 for an 8.5 MJ implosion. While the use of 1D simulations limits the accuracy of these results, they indicate a sufficiently high level of performance to warrant further investigations and verification of this new low-instability regime. This potentially suggests an attractive new approach to fusion energy. This article is part of a discussion meeting issue ‘Prospects for high gain inertial fusion energy (part 2)’.

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Fatehi, Rouhollah, Mostafa Safdari Shadloo, and Mehrdad T. Manzari. "Numerical investigation of two-phase secondary Kelvin–Helmholtz instability." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 228, no. 11 (November 26, 2013): 1913–24. http://dx.doi.org/10.1177/0954406213512630.

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Instability of the interface between two immiscible fluids representing the so-called Kelvin–Helmholtz instability problem is studied using smoothed particle hydrodynamics method. Interfacial tension is included, and the fluids are assumed to be inviscid. The time evolution of interfaces is obtained for two low Richardson numbers [Formula: see text] and [Formula: see text] while Bond number varies between zero and infinity. This study focuses on the effect of Bond and Richardson numbers on secondary instability of a two-dimensional shear layer. A brief theoretical discussion is given concerning the linear early time regime followed by numerical investigation of the growth of secondary waves on the main billow. Results show that for [Formula: see text], at all Bond numbers, secondary instabilities start in the early times after a perturbation is imposed, but they grow only for Bond numbers greater than 1. For [Formula: see text], however, secondary instabilities appear only at Bond numbers greater than 10. Finally, based on numerical simulations and using an energy budget analysis involving interfacial potential energy, a quantitative measure is given for the intensity of secondary instabilities using interfacial surface area.

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Andersson, Nils, and Andreas Schmitt. "Dissipation Triggers Dynamical Two-Stream Instability." Particles 2, no. 4 (October 31, 2019): 457–80. http://dx.doi.org/10.3390/particles2040028.

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Two coupled, interpenetrating fluids suffer instabilities beyond certain critical counterflows. For ideal fluids, an energetic instability occurs at the point where a sound mode inverts its direction due to the counterflow, while dynamical instabilities only occur at larger relative velocities. Here, we discuss two relativistic fluids, one of which is dissipative. Using linearized hydrodynamics, we show that, in this case, the energetic instability turns dynamical, i.e., there is an exponentially growing mode, and this exponential growth only occurs in the presence of dissipation. This result is general and does not rely on an underlying microscopic theory. It can be applied to various two-fluid systems, for instance, in the interior of neutron stars. We also point out that, under certain circumstances, the two-fluid system exhibits a mode analogous to the r-mode in neutron stars that can become unstable for arbitrarily small values of the counterflow.

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Ferrara, A., and G. Einaudi. "Hydrodynamics of the hot component of the Galactic halo. II - Radiative and dynamical instabilities." Astrophysical Journal 395 (August 1992): 475. http://dx.doi.org/10.1086/171667.

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Abbasi, Muhammad, Ryungeun Song, Seongsu Cho, and Jinkee Lee. "Electro-Hydrodynamics of Emulsion Droplets: Physical Insights to Applications." Micromachines 11, no. 10 (October 18, 2020): 942. http://dx.doi.org/10.3390/mi11100942.

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The field of droplet electrohydrodynamics (EHD) emerged with a seminal work of G.I. Taylor in 1966, who presented the so-called leaky dielectric model (LDM) to predict the droplet shapes undergoing distortions under an electric field. Since then, the droplet EHD has evolved in many ways over the next 55 years with numerous intriguing phenomena reported, such as tip and equatorial streaming, Quincke rotation, double droplet breakup modes, particle assemblies at the emulsion interface, and many more. These phenomena have a potential of vast applications in different areas of science and technology. This paper presents a review of prominent droplet EHD studies pertaining to the essential physical insight of various EHD phenomena. Here, we discuss the dynamics of a single-phase emulsion droplet under weak and strong electric fields. Moreover, the effect of the presence of particles and surfactants at the emulsion interface is covered in detail. Furthermore, the EHD of multi-phase double emulsion droplet is included. We focus on features such as deformation, instabilities, and breakups under varying electrical and physical properties. At the end of the review, we also discuss the potential applications of droplet EHD and various challenges with their future perspectives.

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Bournaud, Frédéric. "Galaxy formation hydrodynamics: From cosmic flows to star-forming clouds." Proceedings of the International Astronomical Union 6, S270 (May 2010): 491–98. http://dx.doi.org/10.1017/s174392131100086x.

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AbstractMajor progress has been made over the last few years in understanding hydrodynamical processes on cosmological scales, in particular how galaxies get their baryons. There is increasing recognition that a large part of the baryons accrete smoothly onto galaxies, and that internal evolution processes play a major role in shaping galaxies – mergers are not necessarily the dominant process. However, predictions from the various assembly mechanisms are still in large disagreement with the observed properties of galaxies in the nearby Universe. Small-scale processes have a major impact on the global evolution of galaxies over a Hubble time and the usual sub-grid models account for them in a far too uncertain way. Understanding when, where and at which rate galaxies formed their stars becomes crucial to understand the formation of galaxy populations. I discuss recent improvements and current limitations in “resolved” modeling of star formation, aiming at explicitly capturing star-forming instabilities, in cosmological and galaxy-sized simulations. Such models need to develop three-dimensional turbulence in the ISM, which requires parsec-scale resolution at redshift zero.

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CHIRAVALLE, VINCENT P. "The k-L turbulence model for describing buoyancy-driven fluid instabilities." Laser and Particle Beams 24, no. 3 (September 2006): 381–94. http://dx.doi.org/10.1017/s026303460606054x.

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The k-L turbulence model, where k is the turbulent kinetic energy and L represents the turbulent eddy scale length, is a two-equation turbulence model that has been proposed to simulate turbulence induced by Rayleigh-Taylor (RT) and Richtmyer Meshkov (RM) instabilities, which play an important role in the implosions of inertial confinement fusion (ICF) capsule targets. There are three free parameters in the k-L model, and in this paper, I calibrate them independently by comparing with RT and RM data from the linear electric motor (LEM) experiments together with classical Kelvin-Helmoholtz (KH) data. To perform this calibration, I numerically solved the equations of one-dimensional (1D) Lagrangian hydrodynamics, in a manner similar to that of contemporary ICF codes, together with the k-L turbulence model. With the three free parameters determined, I show that the k-L model is successful in describing both shear-driven and buoyancy-driven instabilities, capturing the experimentally observed separation between bubbles and spikes at high Atwood number for the RT case, as well as the temporal mix width recorded in RM shock tube experiments.

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Anninos, Wenbo Y., Michael L. Norman, and Peter Anninos. "Nonlinear Hydrodynamics of Cosmological Sheets. II. Fragmentation and the Gravitational, Cooling, and Thin-Shell Instabilities." Astrophysical Journal 450 (September 1995): 1. http://dx.doi.org/10.1086/176112.

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Simha, R. Aditi, and Sriram Ramaswamy. "Statistical hydrodynamics of ordered suspensions of self-propelled particles: waves, giant number fluctuations and instabilities." Physica A: Statistical Mechanics and its Applications 306 (April 2002): 262–69. http://dx.doi.org/10.1016/s0378-4371(02)00503-4.

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Mukhopadhyay, Sanghasri, and Asim Mukhopadhyay. "Hydrodynamics and instabilities of falling liquid film over a non-uniformly heated inclined wavy bottom." Physics of Fluids 32, no. 7 (July 1, 2020): 074103. http://dx.doi.org/10.1063/5.0010461.

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Liebendörfer, M., S. Whitehouse, and T. Fischer. "Toward three-dimensional simulations of stellar core collapse with magnetic fields." Proceedings of the International Astronomical Union 2, S239 (August 2006): 326–28. http://dx.doi.org/10.1017/s1743921307000683.

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AbstractIn spherical symmetry, very reliable models of stellar core collapse, bounce, and the postbounce phase can be constructed based on general relativistic Boltzmann neutrino transport. However, even if the time-integrated neutrino luminosity in the region between the surface of the protoneutron star and the stalled accretion shock is one or two orders of magnitude larger than the energy of a supernova explosion, it is generally accepted that the net energy transfer is not efficient enough to drive an explosion, unless the fluid instabilities in this regime are taken into account. Complementary to other groups, who are elaborating an extension of the accurate neutrino physics to axisymmetric simulations, we construct efficient parameterizations of the neutrino physics that enable three-dimensional magneto-hydrodynamics simulations that do not constrain the fluid instabilities by artificially imposed symmetries. We evaluate our approximations with respect to spherically symmetric Boltzmann neutrino transport, present preliminary MHD simulations with a resolution of 600 zones cubed, and illustrate the questions that can be addressed by this approach.

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Nagasawa, Mikio. "Three Dimensional Hydrodynamical Simulation of Type II Supernova." Highlights of Astronomy 8 (1989): 213–14. http://dx.doi.org/10.1017/s1539299600007796.

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AbstractAdiabatic supernova explosions of polytropic stars are investigated by a three dimensional Smoothed Particle Hydrodynamics. The evolution of thermal point explosions is almost spherically symmetric in a global sense, but they are found to be unstable against Rayleigh-Taylor instabilities. The typical unstable wavelength, which grows in the nonlinear stage, is comparable to the thickness of the spherical shell. As a result, we find a porous density structure on the expanding shell. These results suggest the dumpiness of the ejecta of supernova explosions. The accompanying mixing motion in the expanding shell can explain the rapidly rising light curve of SN1987A. Because it may mix up the energy source 56Ni towards the outer layers of supernovae.

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Lin, Jun, Hakim Naceur, Daniel Coutellier, and Abdel Laksimi. "Geometrically nonlinear analysis of two-dimensional structures using an improved smoothed particle hydrodynamics method." Engineering Computations 32, no. 3 (May 5, 2015): 779–805. http://dx.doi.org/10.1108/ec-12-2013-0306.

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Purpose – The purpose of this paper is to present an efficient smoothed particle hydrodynamics (SPH) method particularly adapted for the geometrically nonlinear analysis of structures. Design/methodology/approach – In order to resolve the inconsistency phenomenon which systematically occurs in the standard SPH method at the domain’s boundaries of the studied structure, the classical kernel function and its spatial derivatives were modified by the use of Taylor series expansion. The well-known tensile instabilities inherent to the Eulerian SPH formulation were attenuated by the use of the Total Lagrangian Formulation (TLF). Findings – In order to demonstrate the effectiveness of the present improved SPH method, several numerical applications involving geometrically nonlinear behaviors were carried out using the explicit dynamics scheme for the time integration of the PDEs. Comparisons of the obtained results using the present SPH model with analytical reference solutions and with those obtained using ABAQUS finite element (FE) commercial software, show its good accuracy and robustness. Practical implications – An additional application including a multilayered composite structure and involving buckling and delamination was investigated using the present improved SPH model and the results are compared to the FE results, they confirmed both the efficiency and the accuracy of the proposed method. Originality/value – An efficient 2D-continuum SPH model for the geometrically nonlinear analysis of thin and thick structures is proposed. Contrarily to the classical SPH approaches, here the constitutive material relations are used to link naturally the stresses and strains. The Total Lagrangian approach is investigated to alleviate the tensile instabilities problem, allowing at the same time to avoid the updating procedure of the neighboring particles search and therefore reducing CPU usage. The proposed approach is valid for isotropic and multilayered composites structures undergoing large transformations. CPU time savings and better results with the new 2D-continuum SPH formulation compared to the classical continuum SPH. The explicit dynamic scheme was used for time integration allowing a fast resolution algorithm even for highly nonlinear problems.

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