The effect of viscosity on the flow morphology in semidetached binary systems. Results of 3D simulations. II

Bisikalo, D. V.; Boyarchuk, A. A.; Кузнецов, О. А.; Чечеткин, В. М.

doi:10.1134/1.163824

Cited by 55 publications

(60 citation statements)

References 12 publications

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“…These results were not analyzed in Flebbe et al (1992Flebbe et al ( , 1994, where the authors developed SPH viscous formulations and applied the code to the same numerical tests, showing that the shear component of the stress tensor is proportional to the α ss parameter times the gas pressure, excluding any artificial viscosity contribution. In Bisikalo et al (2000), adopting an Eulerian finite difference method and various physical viscosities, they found a self consistent solution showing the absence of shock interactions between the stream flowing from L1, the disk body and its outer edge, and the similarity of flow patterns adopting different disc viscosities.…”

Section: Role Of Physical Viscosity On Disc Morphology Dynamics and mentioning

confidence: 99%

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Spiral and shock front development in accretion discs in close binaries: Physically viscous and non-viscous SPH modelling

Lanzafame

2003

A&A

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Abstract.A comparison between an accretion disc model, whose transport mechanisms are driven only by artificial viscosity, and a physically viscous accretion disc model for the same close binary system is performed here by adopting the same parameters and boundary conditions. These assumptions mean that artificial viscosity, included in both models, shares, together with physical viscosity, mass and angular momentum transport in the second disc model. The Smooth Particle Hydrodynamics (SPH) Lagrangian scheme has been adopted in both models and α ss = 1 has been considered as for the viscous model according to the well-known Shakura and Sunjaev formulation. Physical viscosity is represented by the viscous force contribution as a divergence of the symmetric viscous stress tensor in the Navier-Stokes equation, whilst the viscous energy contribution is given by a symmetric combination of the symmetric shear tensor times to the particle velocity. Adopting a supersonic particle inflowing at the inner lagrangian point L1, clear spiral strong shocks in the radial flux develop from the inviscid 3D model. Extended spirals and shock fronts are even more evident in the viscous accretion disc model, which is larger than the non-viscous one in the XY orbital plane. Characteristics of the two disc structures as well as observational consequences are discussed.

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Section: Role Of Physical Viscosity On Disc Morphology Dynamics and mentioning

confidence: 99%

“…In fact, other authors such as Flebbe et al (1992Flebbe et al ( , 1994, Bisikalo et al (2000), who also included physical viscosity, did not mention anything about the existence of spirals and spiral shocks in their models.…”

Section: Introductionmentioning

confidence: 99%

Spiral and shock front development in accretion discs in close binaries: Physically viscous and non-viscous SPH modelling

Lanzafame

2003

A&A

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“…The basic problem here is whether the interaction between the stream and the disk remains shockless, as was shown for relatively hot disks [1,3,4,8,14]. Section 5 presents our main conclusions and a physical basis for the universal nature of the shockless interaction between the stream and disk.…”

Section: Introductionmentioning

confidence: 99%

“…In 1999-2002, we developed a three-dimensional, gas-dynamical model and used it to study the flow patterns in binary systems [1][2][3][4][5][6][7][8][9][10][11][12][13][14]. These studies indicate that the flow structure is substantially affected by rarefied gas of the intercomponent envelope.…”

Section: Introductionmentioning

confidence: 99%

Morphology of the interaction between the stream and cool accretion disk in a semidetached binary system

et al. 2003

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We analyze heating and cooling processes in accretion disks in binaries. For realistic parameters of the accretion disks in close binaries (• M ≃ 10 −12 ÷ 10 −7 M ⊙ /year and α ≃ 10 −1 ÷ 10 −2 ), the gas temperature in the outer parts of the disk is ∼ 10 4 K to ∼ 10 6 K. Our previous gas-dynamical studies of mass transfer in close binaries indicate that, for hot disks (with temperatures for the outer parts of the disk of several hundred thousand K), the interaction between the stream from the inner Lagrange point and the disk is shockless. To study the morphology of the interaction between the stream and a cool accretion disk, we carried out three-dimensional modeling of the flow structure in a binary for the case when the gas temperature in the outer parts of the forming disk does not exceed 13 600 K. The flow pattern indicates that the interaction is again shockless. The computations provide evidence that, as is the case for hot disks, the zone of enhanced energy release (the "hot line") is located beyond the disk, and originates due to the interaction between the circum-disk halo and the stream.

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“…However, they adopted a shear component of the stress tensor proportional to the α Shakura and Sunjaev parameter times the gas pressure and excluded any artificial viscosity contribution. Bisikalo et al (2000), adopting γ = 1.01, an Eulerian finite difference method and various physical viscosities, found self-consistent solutions showing the absence of a shock impact between the stream flowing from L1 and the disk body at its outer edge. They also found a similarity of the flow patterns even adopting different disc viscosities.…”

Section: Introductionmentioning

confidence: 99%

Low compressibility accretion disc formation in close binaries: the role of physical viscosity

Lanzafame

Belvedère

Molteni

2006

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Aims. Physical viscosity naturally hampers gas dynamics (rarefaction or compression). Such a role should support accretion disc development inside the primary gravitation potential well in a close binary system, even for low compressibility modelling. Therefore, from the astrophysical point of view, highly viscous accretion discs could exist even in the low compressibility regime showing strong thermal differences to high compressibility ones Methods. We performed simulations of stationary Smooth Particle Hydrodynamics (SPH) low compressibility accretion disc models for the same close binary system. Artificial viscosity operates in all models. The absence of physical viscosity and a supersonic high mass transfer characterize the first model. Physical viscosity and the same supersonic high mass transfer characterize the second model, whilst physical viscosity and a subsonic low mass transfer characterize the third model. The same binary system parameters, such as stellar masses and their separation, have been adopted, as well as the same polytropic index γ = 5/3. Thus we investigated the role of physical viscosity in mass and angular momentum transport in the two viscid models and compare them to the inviscid model. An initial value of the parameter α = 1 has been considered for the physically viscous models, according to the well-known Shakura and Sunjaev formulation, but simulations were carried out also for α = 0.1 and α = 0.5 in the case of a supersonic mass transfer. Physical viscosity is represented by the viscous force contribution expressed by the divergence of the symmetric viscous stress tensor in the Navier-Stokes equation, while the viscous energy contribution is given by a symmetric combination of the symmetric shear tensor times the particle velocity. Results. The results show that physical viscosity supports and favours accretion disc formation despite the very low compressibility assumed. On the contrary, in the inviscid case no evident disc structure appears. In all models neither shock fronts nor extended clear spirals in the radial flow develop.

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The effect of viscosity on the flow morphology in semidetached binary systems. Results of 3D simulations. II

Cited by 55 publications

References 12 publications

Spiral and shock front development in accretion discs in close binaries: Physically viscous and non-viscous SPH modelling

Spiral and shock front development in accretion discs in close binaries: Physically viscous and non-viscous SPH modelling

Morphology of the interaction between the stream and cool accretion disk in a semidetached binary system

Low compressibility accretion disc formation in close binaries: the role of physical viscosity

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