Studying the influence of turbulent mixing on thermonuclear burning regimes during X-ray bursts of neutron stars using the K ε model

Симоненко, В. А.; Gryaznykh, D. A.; Karlykhanov, N. G.; Лыков, В. А.; Shushlebin, A. N.

doi:10.1134/s1063773707020028

Cited by 5 publications

(5 citation statements)

References 16 publications

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“…In this paper the 1D model of turbulence generation by the RTL instability at the flame interface together with the impact of turbulence on the flame is considered. A similar to our model was proposed in [15] for the problems of thermonuclear burning on a surface of neutron stars. The Section II presents the model of turbulence, the setup of the problem for WD together with numerical approach used is presented in Section III, Section IV contains results of simulations, the discussion is presented in Section V.…”

Section: Introductionmentioning

confidence: 58%

Turbulence model for simulation of the flame front propagation in SNIa

Glazyrin

2014

Astrophys Space Sci

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Turbulence significantly influences the dynamics of flame in SNIa. The large Reynolds number makes impossible the direct numerical simulations of turbulence, and different models of turbulence have to be used. Here we present the simulations with the k-ǫ model. The turbulence is generated by the RTL instability and crucially influences flame front velocity, resulting in v flame ∼ 300 km/s. The model reproduces turbulent properties in low-dimensional simulations and can be used for the low-cost studies.

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Section: Introductionmentioning

confidence: 58%

Turbulence model for simulation of the flame front propagation in SNIa

Glazyrin

2014

Astrophys Space Sci

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“…In the latter, the small-scale turbulent processes are described in terms of the phenomenological K model (a subgrid description; see Simonenko et al 2007), while the large-scale processes (the formation of vorticity of the onflowing matter at the burning wave front) are described by direct gasdynamic simulations. The results of our studies performed with this code will be presented in the next publication.…”

Section: Discussionmentioning

confidence: 99%

“…The formulas for the equation of state and the radiation mean free path are given and substantiated in Simonenko et al (2007). The formulation of the model problem was simplified noticeably, because we sought to achieve not the maximum accuracy of our results but only qualitative agreement.…”

Section: Formulation Of the Problemmentioning

confidence: 99%

“…The latter affects both the local propagation of burning and the spreading rate of burning products in the upper atmosphere. To describe turbulent mixing, we use the K model (its applicability was discussed previously (Simonenko et al 2007)). These possibilities were realized in the 2D TIGR-3T code, in which the gasdynamic processes are described by an explicit finite-difference method on an Euler-Lagrange mesh.…”

Section: Introductionmentioning

confidence: 99%

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Mechanism of thermonuclear burning propagation in a helium layer on a neutron star surface: A simplified adiabatic model

et al. 2012

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Some thermonuclear X-ray bursters exhibit a high-frequency (about 300 Hz or more) brightness modulation at the rising phase of some bursts. These oscillations are explained by inhomogeneous heating of the surface layer on a rapidly rotating neutron star due to the finite propagation speed of thermonuclear burning. We suggest and substantiate a mechanism of this propagation that is consistent with experimental data. Initially, thermonuclear ignition occurs in a small region of the neutron star surface layer. The burning products rapidly rise and spread in the upper atmospheric layers due to turbulent convection. The accumulation of additional matter leads to matter compression and ignition at the bottom of the layer. This determines the propagation of the burning front. To substantiate this mechanism, we use the simplifying assumptions about a helium composition of the neutron star atmosphere and its initial adiabatic structure with a density of 1.75 × 10 8 g cm −3 at the bottom. 2D numerical simulations have been performed using a modified particle method in the adiabatic approximation.

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“…The applicability of the K model for modeling explosive astrophysical processes was justified previously (Simonenko et al 2007 The formulation of the test problem we chose was similar to the formulations in Fryxell and Woosely (1982a) and Zingale et al (2001) and coincided with the problem modeled with the MPM code and described in our first paper. The only significant difference was the following: the longitudinal size of the layer was appreciably shorter and equal to 500 m.…”

Section: The Tigr-3t Code and The K Turbulence Modelmentioning

confidence: 99%

Mechanism of thermonuclear burning propagation in a helium layer on a neutron star surface: A refined model with heat conduction and subgrid turbulence

et al. 2012

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Results of 2D numerical simulations of thermonuclear burning propagation in a helium layer on a neutron star surface using the Euler-Lagrange TIGR-3T code are presented. This process is crucial for the development of type I X-ray bursts. Ignition and thermonuclear burning propagation are fairly easy to obtain when simulating a layer with a density at the bottom of 1.75 × 10 8 g cm −3 . Such a simulation allows it to be compared with previous simulations based on other codes, including the simulation based on the MPM code described previously. However, this density is two orders of magnitude higher than can be obtained in observed bursters. The implementation of efficient numerical methods for the description of heat conduction and turbulence in the TIGR-3T code has allowed simulations to be performed for a layer with a density at the bottom of 1.8 × 10 7 g cm −3 . The fulfilment of certain conditions on the size and shape of the initial temperature perturbation is required for the propagation of thermonuclear burning. Simulations reveal a peculiar burning propagation mechanism through compression of the layer ahead of the burning front by the matter transferred above the free surface.

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Studying the influence of turbulent mixing on thermonuclear burning regimes during X-ray bursts of neutron stars using the K ε model

Cited by 5 publications

References 16 publications

Turbulence model for simulation of the flame front propagation in SNIa

Turbulence model for simulation of the flame front propagation in SNIa

Mechanism of thermonuclear burning propagation in a helium layer on a neutron star surface: A simplified adiabatic model

Mechanism of thermonuclear burning propagation in a helium layer on a neutron star surface: A refined model with heat conduction and subgrid turbulence

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