Three‐dimensional Hydrodynamic Simulations of Accretion Tori in Kerr Spacetimes

2002 ◽  
Vol 577 (2) ◽  
pp. 866-879 ◽  
Author(s):  
Jean‐Pierre De Villiers ◽  
John F. Hawley
Keyword(s):  
Three Dimensional ◽  
Hydrodynamic Simulations

scholarly journals Rotational Effects on Reynolds Stresses in the Solar Convection Zone

1991 ◽  
Vol 130 ◽  
pp. 98-100
Author(s):  
P. Pulkkinen ◽  
I. Tuominen ◽  
A. Brandenburg ◽  
Å. Nordlund ◽  
R.F. Stein
Keyword(s):  
Reynolds Stress ◽  
Convection Zone ◽  
Rotation Axis ◽  
Three Dimensional ◽  
External Parameter ◽  
Reynolds Stresses ◽  
Solar Convection Zone ◽  
Hydrodynamic Simulations ◽  
Solar Convection ◽  
Good Agreement

AbstractThree-dimensional hydrodynamic simulations are carried out in a rectangular box. The angle between gravity and rotation axis is kept as an external parameter in order to study the latitude-dependence of convection. Special attention is given to the horizontal Reynolds stress and the ∧-effect (Rüdiger, 1989). The results of the simulations are compared with observations and theory and a good agreement is found.

scholarly journals High-resolution three-dimensional simulations of gas removal from ultrafaint dwarf galaxies

2019 ◽  
Vol 630 ◽  
pp. A140 ◽  
Author(s):  
Donatella Romano ◽  
Francesco Calura ◽  
Annibale D’Ercole ◽  
C. Gareth Few
Keyword(s):  
High Resolution ◽  
Milky Way ◽  
Dwarf Galaxies ◽  
Three Dimensional ◽  
Energy Output ◽  
Potential Well ◽  
Hydrodynamic Simulations ◽  
Stellar Feedback ◽  
Gas Removal ◽  
Cold Gas

Context. The faintest Local Group galaxies found lurking in and around the Milky Way halo provide a unique test bed for theories of structure formation and evolution on small scales. Deep Subaru and Hubble Space Telescope photometry demonstrates that the stellar populations of these galaxies are old and that the star formation activity did not last longer than 2 Gyr in these systems. A few mechanisms that may lead to such a rapid quenching have been investigated by means of hydrodynamic simulations, but these have not provided any final assessment so far. Aims. This is the first in a series of papers aimed at analyzing the roles of stellar feedback, ram pressure stripping, host-satellite tidal interactions, and reionization in cleaning the lowest mass Milky Way companions of their cold gas using high-resolution, three-dimensional hydrodynamic simulations. Methods. We simulated an isolated ultrafaint dwarf galaxy loosely modeled after Boötes I, and examined whether or not stellar feedback alone could drive a substantial fraction of the ambient gas out from the shallow potential well. Results. In contrast to simple analytical estimates, but in agreement with previous hydrodynamical studies, we find that most of the cold gas reservoir is retained. Conversely, a significant amount of the metal-enriched stellar ejecta crosses the boundaries of the computational box with velocities exceeding the local escape velocity and is, thus, likely lost from the system. Conclusions. Although the total energy output from multiple supernova explosions exceeds the binding energy of the gas, no galactic-scale outflow develops in our simulations and as such, most of the ambient medium remains trapped within the weak potential well of the model galaxy. It seems thus unavoidable that to explain the dearth of gas in ultrafaint dwarf galaxies, we will have to resort to environmental effects. This will be the subject of a forthcoming paper.

scholarly journals Synergetic Growth of the Rayleigh–Taylor and Richtmyer–Meshkov Instabilities in the Relativistic Jet

2016 ◽  
Vol 12 (S324) ◽  
pp. 87-88
Author(s):  
Jin Matsumoto ◽  
Youhei Masada
Keyword(s):  
External Medium ◽  
Ambient Medium ◽  
Three Dimensional ◽  
Specific Enthalpy ◽  
Hydrodynamic Simulations ◽  
Calculation Domain ◽  
Relativistic Jet ◽  
Material Mixing

AbstractWe investigate the growth of the Rayleigh–Taylor and Richtmyer–Meshkov instabilities at the interface of the relativistic jet using three-dimensional hydrodynamic simulations. The propagation of the relativistic jet that is continuously injected from the boundary of the calculation domain into a uniform ambient medium is solved. We find that the interface of the jet is deformed by a synergetic growth of the Rayleigh–Taylor and Richtmyer–Meshkov instabilities regardless of the launching condition, such as the specific enthalpy of the jet or the effective inertia ratio between the jet and ambient medium. The material mixing between the jet and external medium due to these instabilities causes the deceleration of the jet.

scholarly journals Three-dimensional hydrodynamic simulations ofL2Puppis

2016 ◽  
Vol 460 (4) ◽  
pp. 4182-4187 ◽  
Author(s):  
Zhuo Chen ◽  
Jason Nordhaus ◽  
Adam Frank ◽  
Eric G. Blackman ◽  
Bruce Balick
Keyword(s):  
Three Dimensional ◽  
Hydrodynamic Simulations

scholarly journals Time-dependent Turbulence in Stars

2010 ◽  
Vol 6 (S271) ◽  
pp. 205-212
Author(s):  
W. David Arnett ◽  
Casey Meakin
Keyword(s):  
Stellar Evolution ◽  
Three Dimensional ◽  
Red Giants ◽  
Global Instability ◽  
Lorenz Model ◽  
Hydrodynamic Simulations ◽  
Nuclear Burning ◽  
Mixing Length Theory ◽  
Convective Layer ◽  
Random Fluctuations

AbstractThree-dimensional (3D) hydrodynamic simulations of shell oxygen burning by Meakin & Arnett (2007b) exhibit bursty, recurrent fluctuations in turbulent kinetic energy. These are shown to be due to a global instability in the convective region, which has been suppressed in simulations of stellar evolution which use mixing-length theory (MLT). Quantitatively similar behavior occurs in the model of a convective roll (cell) of Lorenz (1963), which is known to have a strange attractor that gives rise to random fluctuations in time. An extension of the Lorenz model, which includes Kolmogorov damping and nuclear burning, is shown to exhibit bursty, recurrent fluctuations like those seen in the 3D simulations. A simple model of a convective layer (composed of multiple Lorenz cells) gives luminosity fluctuations which are suggestive of irregular variables (red giants and supergiants, see Schwarzschild (1975). Details and additional discussion may be found in Arnett & Meakin (2011).Apparent inconsistencies between Arnett, Meakin, & Young (2009) and Nordlund, Stein, & Asplund (2009) on the nature of convective driving have been resolved, and are discussed.

scholarly journals Cooling and instabilities in colliding flows

2021 ◽  
Author(s):  
R N Markwick ◽  
A Frank ◽  
J Carroll-Nellenback ◽  
B Liu ◽  
E G Blackman ◽  
...  
Keyword(s):  
Thermal Instability ◽  
Three Dimensional ◽  
Oscillation Period ◽  
Three Dimensions ◽  
Temperature Dependent ◽  
Radiative Shock ◽  
Hydrodynamic Simulations ◽  
Protostellar Jets ◽  
The One ◽  
Cooling Function

Abstract Collisional self-interactions occurring in protostellar jets give rise to strong shocks, the structure of which can be affected by radiative cooling within the flow. To study such colliding flows, we use the AstroBEAR AMR code to conduct hydrodynamic simulations in both one and three dimensions with a power law cooling function. The characteristic length and time scales for cooling are temperature dependent and thus may vary as shocked gas cools. When the cooling length decreases sufficiently rapidly the system becomes unstable to the radiative shock instability, which produces oscillations in the position of the shock front; these oscillations can be seen in both the one and three dimensional cases. Our simulations show no evidence of the density clumping characteristic of a thermal instability, even when the cooling function meets the expected criteria. In the three-dimensional case, the nonlinear thin shell instability (NTSI) is found to dominate when the cooling length is sufficiently small. When the flows are subjected to the radiative shock instability, oscillations in the size of the cooling region allow NTSI to occur at larger cooling lengths, though larger cooling lengths delay the onset of NTSI by increasing the oscillation period.

scholarly journals The i-process yields of rapidly accreting white dwarfs from multicycle He-shell flash stellar evolution models with mixing parametrizations from 3D hydrodynamics simulations

2019 ◽  
Vol 488 (3) ◽  
pp. 4258-4270 ◽  
Author(s):  
Pavel A Denissenkov ◽  
Falk Herwig ◽  
Paul Woodward ◽  
Robert Andrassy ◽  
Marco Pignatari ◽  
...  
Keyword(s):  
Stellar Evolution ◽  
White Dwarfs ◽  
Binary Systems ◽  
Scaling Laws ◽  
Ingestion Rate ◽  
Three Dimensional ◽  
Close Binary ◽  
Convective Boundary ◽  
Retention Efficiency ◽  
Hydrodynamic Simulations

ABSTRACT We have modelled the multicycle evolution of rapidly accreting CO white dwarfs (RAWDs) with stable H burning intermittent with strong He-shell flashes on their surfaces for 0.7 ≤ MRAWD/M⊙ ≤ 0.75 and [Fe/H] ranging from 0 to −2.6. We have also computed the i-process nucleosynthesis yields for these models. The i process occurs when convection driven by the He-shell flash ingests protons from the accreted H-rich surface layer, which results in maximum neutron densities Nn, max ≈ 1013–1015 cm−3. The H-ingestion rate and the convective boundary mixing (CBM) parameter ftop adopted in the one-dimensional nucleosynthesis and stellar evolution models are constrained through three-dimensional (3D) hydrodynamic simulations. The mass ingestion rate and, for the first time, the scaling laws for the CBM parameter ftop have been determined from 3D hydrodynamic simulations. We confirm our previous result that the high-metallicity RAWDs have a low mass retention efficiency ($\eta \lesssim 10{{\ \rm per\ cent}}$). A new result is that RAWDs with [Fe/H] $\lesssim -2$ have $\eta \gtrsim 20{{\ \rm per\ cent}}$; therefore, their masses may reach the Chandrasekhar limit and they may eventually explode as SNeIa. This result and the good fits of the i-process yields from the metal-poor RAWDs to the observed chemical composition of the CEMP-r/s stars suggest that some of the present-day CEMP-r/s stars could be former distant members of triple systems, orbiting close binary systems with RAWDs that may have later exploded as SNeIa.

scholarly journals JET-FLUID STRING FORMATION AND DECAY IN HIGH-ENERGY HEAVY-ION COLLISIONS

2007 ◽  
Vol 16 (07n08) ◽  
pp. 2338-2343 ◽  
Author(s):  
M. ISSE ◽  
T. HIRANO ◽  
R. MIZUKAWA ◽  
A. OHNISHI ◽  
K. YOSHINO ◽  
...  
Keyword(s):  
Heavy Ion Collisions ◽  
Three Dimensional ◽  
Heavy Ion ◽  
High Energy ◽  
Fragmentation Model ◽  
Color Singlet ◽  
Hydrodynamic Simulations ◽  
Ion Collisions ◽  
String Formation

We propose a new hadronization mechanism, jet-fluid string (JFS) formation and decay, to understand observables in intermediate to high-pT regions comprehensively. In the JFS model, hard partons produced in jet lose their energy in traversing the QGP fluid, which is described by fully three-dimensional hydrodynamic simulations. When a jet parton escapes from the QGP fluid, it picks up a partner parton from a fluid and forms a color singlet string, then it decays to hadrons. We find that high-pTv2 values in JFS are about two times larger than in the independent fragmentation model.

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