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9 Publications visible to you, out of a total of 9
Dynamics in a stellar convective layer and at its boundary: Comparison of five 3D hydrodynamics codes

Abstract

Not specified

Authors: R. Andrassy, J. Higl, H. Mao, M. Mocák, D. G. Vlaykov, W. D. Arnett, I. Baraffe, S. W. Campbell, T. Constantino, P. V. F. Edelmann, T. Goffrey, T. Guillet, F. Herwig, R. Hirschi, L. Horst, G. Leidi, C. Meakin, J. Pratt, F. Rizzuti, F. K. Röpke, P. Woodward

Date Published: 1st Mar 2022

Publication Type: Journal

Simulations of hydrodynamic phenomena in stellar interiors

Abstract (Expand)

This thesis presents multidimensional hydrodynamic simulations of stellar interiors with a focus on dynamical phenomena at low Mach numbers using the Seven-League Hydro (SLH) code. A better understanding … of these phenomena is crucial to improve the modeling of stellar evolution. It is demonstrated that suitable numerical methods are required to avoid that numerical artifacts and spurious dissipation dominate the actual physical flow. Three-dimensional simulations of convective helium shell burning are used to measure the entrainment of mass into the convective region. This aids the parametrization of entrainment in one-dimensional evolution calculations. Furthermore, the excitation of waves by core convection is simulated and the results are analyzed regarding their physical plausibility and agreement with observations. These simulations demonstrate that the current set of numerical methods used by the SLH code is promising regarding future, more realistic simulations of astrophysical flows.

Author: Leonhard Horst

Date Published: 10th Dec 2021

Publication Type: Doctoral Thesis

Multidimensional low-Mach number time-implicit hydrodynamic simulations of convective helium shell burning in a massive star

Abstract

Not specified

Authors: L. Horst, R. Hirschi, P. V. F. Edelmann, R. Andrássy, F. K. Röpke

Date Published: 1st Sep 2021

Publication Type: Journal

Collective velocity broadening from gravity waves as a plausible mechanism for macroturbulence in massive stars

Abstract

Not specified

Authors: D. M. Bowman, S. Burssens, S. Simón-Dı́az, P. V. F. Edelmann, T. M. Rogers, L. Horst, F. K. Röpke, C. Aerts

Date Published: 1st Sep 2021

Publication Type: InProceedings

Well-balanced treatment of gravity in astrophysical fluid dynamics simulations at low Mach numbers

Abstract

Not specified

Authors: P. V. F. Edelmann, L. Horst, J. P. Berberich, R. Andrassy, J. Higl, G. Leidi, C. Klingenberg, F. K. Röpke

Date Published: 1st Aug 2021

Publication Type: Journal

VizieR Online Data Catalog: OB stars TESS phot. & high-resolution spectroscopy (Bowman+, 2020)

Abstract

Not specified

Authors: D. M. Bowman, S. Burssens, S. Simon-Diaz, P. V. F. Edelmann, T. M. Rogers, L. Horst, F. K. Ropke, C. Aerts

Date Published: 1st Oct 2020

Publication Type: Journal

Fully compressible simulations of waves and core convection in main-sequence stars

Abstract (Expand)

Context. Recent, nonlinear simulations of wave generation and propagation in full-star models have been carried out in the anelastic approximation using spectral methods. Although it makes long time … steps possible, this approach excludes the physics of sound waves completely and requires rather high artificial viscosity and thermal diffusivity for numerical stability. A direct comparison with observations is thus limited. Aims. We explore the capabilities of our compressible multidimensional Seven-League Hydro (SLH) code to simulate stellar oscillations. Methods. We compare some fundamental properties of internal gravity and pressure waves in 2D SLH simulations to linear wave theory using two test cases: (1) an interval gravity wave packet in the Boussinesq limit and (2) a realistic 3 M⊙ stellar model with a convective core and a radiative envelope. Oscillation properties of the stellar model are also discussed in the context of observations. Results. Our tests show that specialized low-Mach techniques are necessary when simulating oscillations in stellar interiors. Basic properties of internal gravity and pressure waves in our simulations are in good agreement with linear wave theory. As compared to anelastic simulations of the same stellar model, we can follow internal gravity waves of much lower frequencies. The temporal frequency spectra of velocity and temperature are flat and compatible with the observed spectra of massive stars. Conclusion. The low-Mach compressible approach to hydrodynamical simulations of stellar oscillations is promising. Our simulations are less dissipative and require less luminosity boosting than comparable spectral simulations. The fully-compressible approach allows for the coupling of gravity and pressure waves in the outer convective envelopes of evolved stars to be studied in the future.

Authors: L. Horst, P. V. F. Edelmann, R. Andrássy, F. K. Röpke, D. M. Bowman, C. Aerts, R. P. Ratnasingam

Date Published: 1st Sep 2020

Publication Type: Journal

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