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Titolo:
3-DIMENSIONAL HYDRODYNAMIC BONDI-HOYLE ACCRETION .2. HOMOGENEOUS MEDIUM AT MACH 3 WITH GAMMA=5 3/
Autore:
RUFFERT M; ARNETT D;
Indirizzi:
MAX PLANCK INST ASTROPHYS,POSTFACH 1523 D-85740 GARCHING GERMANY UNIV ARIZONA,STEWARD OBSERV TUCSON AZ 85724
Titolo Testata:
The Astrophysical journal
fascicolo: 1, volume: 427, anno: 1994,
parte:, 1
pagine: 351 - 376
SICI:
0004-637X(1994)427:1<351:3HBA.H>2.0.ZU;2-D
Fonte:
ISI
Lingua:
ENG
Soggetto:
ADAPTIVE MESH REFINEMENT; NUMERICAL SIMULATIONS; WIND ACCRETION; INHOMOGENEOUS-MEDIUM; DYNAMICAL FRICTION; FLOW; STABILITY; GAS; INSTABILITY; LINE;
Keywords:
ACCRETION, ACCRETION DISKS; BINARIES, CLOSE; HYDRODYNAMICS; NOVAE, CATACLYSMIC VARIABLES; SHOCK WAVES;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
57
Recensione:
Indirizzi per estratti:
Citazione:
M. Ruffert e D. Arnett, "3-DIMENSIONAL HYDRODYNAMIC BONDI-HOYLE ACCRETION .2. HOMOGENEOUS MEDIUM AT MACH 3 WITH GAMMA=5 3/", The Astrophysical journal, 427(1), 1994, pp. 351-376

Abstract

We investigate the hydrodynamics of three-dimensional classical Bondi-Hoyle accretion. Totally absorbing spheres of varying sizes (from 10 down to 0.01 accretion radii) move at Mach 3 relative to a homogeneousand slightly perturbed medium, which is taken to be an ideal gas (gamma = 5/3). To accommodate the long-range gravitational forces, the extent of the computational volume is 32(3) accretion radii. We examine the influence of numerical procedure on physical behavior. The hydrodynamics is modeled by the ''piecewise parabolic method. '' No energy sources (nuclear burning) or sinks (radiation, conduction) are included. The resolution in the vicinity of the accretor is increased by multiplynesting several (5-10) grids around the sphere, each finer grid beinga factor of 2 smaller in zone dimension that the next coarser grid. The largest dynamic range (ratio of size of the largest grid to size ofthe finest zone) is 16,384. This allows us to include a coarse model for the surface of the accretor (vacuum sphere) on the finest grid, while at the same time evolving the gas on the coarser grids. Initially (at time t = 0-10), a shock front is set up, a Mach cone develops, andthe accretion column is observable. Eventually the flow becomes unstable, destroying axisymmetry. This happens approximately when the mass accretion rate reaches the values (+/-10%) predicted by the Bondi-Hoyle accretion formula (factor of 2 included). However, our three-dimensional models do not show the highly dynamic flip-flop flow so prominentin two-dimensional calculations performed by other authors. The flow,and thus the accretion rate of all quantities, shows quasi-periodic (P almost-equal-to 5) cycles between quiescent and active states. The interpolation formula proposed in an accompanying paper is found to follow the collected numerical data to within approximately 30%. The specific angular momentum accreted is of the same order of magnitude as the values previously found for two-dimensional flows.

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Documento generato il 27/11/20 alle ore 16:06:44