ANTARES – A Numerical Tool for Astrophysical RESearch with applications to solar granulation

Muthsam, H.; Kupka, F.; Löw-Baselli, Bernhard; Obertscheider, Christof; Langer, Matthias; Lenz, P.

doi:10.1016/j.newast.2009.12.005

Cited by 70 publications

(121 citation statements)

References 36 publications

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“…These are two of the spatial discretizations actually implemented in the ANTARES simulation code, which numerically solves the equations of hydrodynamics and various generalizations thereof [25,23]. When these spatial discretizations are used to solve the heat equation, the stability function R(z) of the RK method (A, b t ), defined by…”

Section: It Turns Out That Ifmentioning

confidence: 99%

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Classical FEM-BEM coupling methods: nonlinearities, well-posedness, and adaptivity

et al. 2012

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Abstract. We construct and analyze strong stability preserving implicit-explicit Runge-Kutta methods for the time integration of models of flow and radiative transport in astrophysical applications. It turns out that in addition to the optimization of the region of absolute monotonicity, other properties of the methods are crucial for the success of the simulations as well. The models in our focus dictate to also take into account the step-size limits associated with dissipativity and positivity of the stiff parabolic terms which represent transport by diffusion. Another important property is uniform convergence of the numerical approximation with respect to different stiffness of those same terms. Furthermore, it has been argued that in the presence of hyperbolic terms, the stability region should contain a large part of the imaginary axis even though the essentially non-oscillatory methods used for the spatial discretization have eigenvalues with a negative real part. Hence, we construct several new methods which differ from each other by taking various or even all of these constraints simultaneously into account. It is demonstrated for the problem of double-diffusive convection that the newly constructed schemes provide a significant computational advantage over methods from the literature. They may also be useful for general problems which involve the solution of advectiondiffusion equations, or other transport equations with similar stability requirements.

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Section: It Turns Out That Ifmentioning

confidence: 99%

“…simulations of double-diffusive convection in an idealized setting performed with the hydrodynamics code ANTARES [25]. Since the ANTARES code and the setting are described in detail in [23], we will restrict ourselves to the results.…”

Section: Numerical Experimentsmentioning

confidence: 99%

Classical FEM-BEM coupling methods: nonlinearities, well-posedness, and adaptivity

et al. 2012

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“…3.2 below). Bruls et al (1999), Vögler et al (2005) and Muthsam et al (2010) employ the short characteristics method (Mihalas et al 1978;Olson & Kunasz 1987;Kunasz & Auer 1988), where the radiative transfer equation is solved on characteristics which only extend to the adjacent upwind and downwind grid layers. This method is required by our choice of iteration technique for an efficient solution of the scattering problem.…”

Section: The Numerical Implementationmentioning

confidence: 99%

Radiative transfer with scattering for domain-decomposed 3D MHD simulations of cool stellar atmospheres

Hayek

Asplund

Carlsson

et al. 2010

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Aims. We present the implementation of a radiative transfer solver with coherent scattering in the new BIFROST code for radiative magneto-hydrodynamical (MHD) simulations of stellar surface convection. The code is fully parallelized using MPI domain decomposition, which allows for large grid sizes and improved resolution of hydrodynamical structures. We apply the code to simulate the surface granulation in a solar-type star, ignoring magnetic fields, and investigate the importance of coherent scattering for the atmospheric structure. Methods. A scattering term is added to the radiative transfer equation, requiring an iterative computation of the radiation field. We use a short-characteristics-based Gauss-Seidel acceleration scheme to compute radiative flux divergences for the energy equation. The effects of coherent scattering are tested by comparing the temperature stratification of three 3D time-dependent hydrodynamical atmosphere models of a solar-type star: without scattering, with continuum scattering only, and with both continuum and line scattering. Results. We show that continuum scattering does not have a significant impact on the photospheric temperature structure for a star like the Sun. Including scattering in line-blanketing, however, leads to a decrease of temperatures by about 350 K below log 10 τ 5000 < ∼ −4. The effect is opposite to that of 1D hydrostatic models in radiative equilibrium, where scattering reduces the cooling effect of strong LTE lines in the higher layers of the photosphere. Coherent line scattering also changes the temperature distribution in the high atmosphere, where we observe stronger fluctuations compared to a treatment of lines as true absorbers.

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“…A comprehensive overview on the numerical details of this code is presented in Muthsam et al [9] and Zaussinger and Spruit [16]. The interior domain consists of several layers 'peeled off' from the boundary of the underlaying convective zone.…”

Section: Numerical Setupmentioning

confidence: 99%

Semi-convective layer formation

Zaussinger

Kupka

Egbers

et al. 2017

J. Phys.: Conf. Ser.

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ANTARES – A Numerical Tool for Astrophysical RESearch with applications to solar granulation

Cited by 70 publications

References 36 publications

Classical FEM-BEM coupling methods: nonlinearities, well-posedness, and adaptivity

Classical FEM-BEM coupling methods: nonlinearities, well-posedness, and adaptivity

Radiative transfer with scattering for domain-decomposed 3D MHD simulations of cool stellar atmospheres

Semi-convective layer formation

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