Three-dimensional hydrodynamic simulations of narrow-angle-tail radio sources. I - The Begelman, Rees, and Blandford model

1992 ◽  
Vol 393 ◽  
pp. 631 ◽  
Author(s):  
Dinshaw S. Balsara ◽  
Michael L. Norman
Keyword(s):  
Three Dimensional ◽  
Radio Sources ◽  
Hydrodynamic Simulations ◽  
Narrow Angle

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.

A THREE-DIMENSIONAL AZIMUTHAL WIDE-ANGLE MODEL FOR THE PARABOLIC WAVE EQUATION

1999 ◽  
Vol 07 (04) ◽  
pp. 269-286 ◽  
Author(s):  
CHIFANG CHEN ◽  
YING-TSONG LIN ◽  
DING LEE
Keyword(s):  
Wave Equation ◽  
Prediction Models ◽  
Three Dimensional ◽  
3D Models ◽  
Theoretical Development ◽  
Wide Angle ◽  
Two Dimensional ◽  
Narrow Angle ◽  
Propagation Prediction ◽  
Dimensional Range

In predicting wave propagations in either direction, the size of the angle of propagation plays an important role; thus, the concept of wide-angle is introduced. Most existing acoustic propagation prediction models do have the capability of treating the wide-angle but the treatment, in practice, is vertical. This is desirable for solving two-dimensional (range and depth) problems. In extending the two-dimensional treatment to 3 dimensions, even though the wide-angle capability is maintained in most 3D models, it is still vertical. Owing to the need of a wide-angle capability in the azimuth direction, this paper formulates an azimuthal wide-angle wave equation whose theoretical development is presented. An illustrative example is included to demonstrate the need for such azimuthal wide-angle capability. Also, a comparison is shown between results using narrow-angle and wide-angle equations separately.

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.

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 Making Faranoff-Riley I radio sources

2019 ◽  
Vol 621 ◽  
pp. A132 ◽  
Author(s):  
S. Massaglia ◽  
G. Bodo ◽  
P. Rossi ◽  
S. Capetti ◽  
A. Mignone
Keyword(s):  
Low Power ◽  
Constant Pressure ◽  
Three Dimensional ◽  
Stratified Medium ◽  
Radio Sources ◽  
Wide Angle ◽  
Mhd Simulations ◽  
The Universe ◽  
Nonrelativistic Velocity

Radio sources of low power are the most common in the universe. Their jets typically move at nonrelativistic velocity and show plume-like morphologies that in many instances appear distorted and bent. We investigate the role of magnetic field on the propagation and evolution of low-power jets and the connection between the field intensity and the resulting morphology. The problem is addressed by means of three-dimensional magnetohydrodynamic (MHD) simulations. We consider supersonic jets that propagate in a stratified medium. The ambient temperature increases with distance from the jet origin maintaining constant pressure. Jets with low magnetization show an enhanced collimation at small distances with respect to hydrodynamic (HD) cases studied in a previous paper. These jets eventually evolve in a way similar to the HD cases. Jets with higher magnetization are affected by strong nonaxisymmetric modes that lead to the sudden jet energy release. From there on, distorted plumes of jet material move at subsonic velocities. This transition is associated with the formation of structures reminiscent of the “warm spots” observed in wide-angle-tail (WAT) sources.

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