A new spherical harmonics scheme for multi-dimensional radiation transport I. Static matter configurations

Radice, David; Abdikamalov, Ernazar; Rezzolla, Luciano; Ott, Christian D.

doi:10.1016/j.jcp.2013.01.048

Cited by 92 publications

(105 citation statements)

References 44 publications

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“…Adding energydependent 3D neutrino transport will increase the computational complexity by an order of magnitude. Novel, highly efficient and scalable approaches to 3D neutrino transport will be needed to address this problem (Sumiyoshi & Yamada 2012;Abdikamalov et al 2012;Zhang et al 2013;Radice et al 2012).…”

Section: Discussionmentioning

confidence: 99%

General-Relativistic Simulations of Three-Dimensional Core-Collapse Supernovae

Ott

Abdikamalov

Mösta

et al. 2013

ApJ

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194

241

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We study the three-dimensional (3D) hydrodynamics of the post-core-bounce phase of the collapse of a 27 M star and pay special attention to the development of the standing accretion shock instability (SASI) and neutrino-driven convection. To this end, we perform 3D general-relativistic simulations with a three-species neutrino leakage scheme. The leakage scheme captures the essential aspects of neutrino cooling, heating, and lepton number exchange as predicted by radiation-hydrodynamics simulations. The 27 M progenitor was studied in 2D by Müller et al., who observed strong growth of the SASI while neutrino-driven convection was suppressed. In our 3D simulations, neutrino-driven convection grows from numerical perturbations imposed by our Cartesian grid. It becomes the dominant instability and leads to large-scale non-oscillatory deformations of the shock front. These will result in strongly aspherical explosions without the need for large-scale SASI shock oscillations. Low--mode SASI oscillations are present in our models, but saturate at small amplitudes that decrease with increasing neutrino heating and vigor of convection. Our results, in agreement with simpler 3D Newtonian simulations, suggest that once neutrino-driven convection is started, it is likely to become the dominant instability in 3D. Whether it is the primary instability after bounce will ultimately depend on the physical seed perturbations present in the cores of massive stars. The gravitational wave signal, which we extract and analyze for the first time from 3D general-relativistic models, will serve as an observational probe of the postbounce dynamics and, in combination with neutrinos, may allow us to determine the primary hydrodynamic instability.

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Section: Discussionmentioning

confidence: 99%

General-Relativistic Simulations of Three-Dimensional Core-Collapse Supernovae

Ott

Abdikamalov

Mösta

et al. 2013

ApJ

Self Cite

194

241

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“…III. The reconstruction method used for most of the simulations is the essentially non-oscillatory method WENO (5 th order weighted-ENO) [13,14], while the other reconstruction methods employed are PPM (the piece-wise parabolic reconstruction method) [45], and MP5 (5 th order monotonicity preserving) [46].…”

Section: Initial Models and Numerical Methodsmentioning

confidence: 99%

Modeling equal and unequal mass binary neutron star mergers using public codes

et al. 2016

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We present three-dimensional simulations of the dynamics of binary neutron star (BNS) mergers from the late stage of the inspiral process up to ∼ 20 ms after the system has merged, either to form a hyper-massive neutron star (NS) or a rotating black hole (BH). We investigate five equalmass models of total gravitational mass 2.207, 2.373, 2.537, 2.697 and 2.854 M , respectively; and four unequal mass models with M ADM 2.53 M and q 0.94, 0.88, 0.83, and 0.77 (whereis the mass ratio). We use a semi-realistic equation of state (EOS), namely the seven-segment piece-wise polytropic SLyPP with a thermal component given by Γ th = 1.8. We have also compared the resulting dynamics (for one model) using both, the BSSN-NOK and CCZ4 methods for the evolution of the gravitational sector, and also different reconstruction methods for the matter sector, namely PPM, WENO and MP5. Our results show agreement and high resolution, but superiority of BSSN-NOK supplemented by WENO reconstruction at lower resolutions.One of the important characteristics of the present investigation is that for the first time, it has been done using only publicly available open source software: the Einstein Toolkit code, deployed for the dynamical evolution; and the LORENE code, for the generation of the initial models. All of the source code and parameters used for the simulations have been made publicly available. This not only makes it possible to re-run and re-analyze our data, but also enables others to directly build upon this work for future research.

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“…One of the main motivations [9] considered in formulating a filtered P n method was to enforce positivity in a spherical harmonics expansion. We write the FP n method using the generalised notation of [10], where the P n expansion (3) with filtering becomes…”

Section: Filtered Spherical Harmonicsmentioning

confidence: 99%

Angular adaptivity with spherical harmonics for Boltzmann transport

Dargaville

Buchan

Smedley-Stevenson

et al. 2019

Journal of Computational Physics

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This paper describes an angular adaptivity algorithm for Boltzmann transport applications which uses P n and filtered P n expansions, allowing for different expansion orders across space/energy. Our spatial discretisation is specifically designed to use less memory than competing DG schemes and also gives us direct access to the amount of stabilisation applied at each node. For filtered P n expansions, we then use our adaptive process in combination with this net amount of stabilisation to compute a spatially dependent filter strength that does not depend on a priori spatial information. This applies heavy filtering only where discontinuities are present, allowing the filtered Pn expansion to retain highorder convergence where possible. Regular and goal-based error metrics are shown and both the adapted P n and adapted filtered P n methods show significant reductions in DOFs and runtime. The adapted filtered P n with our spatially dependent filter shows close to fixed iteration counts and up to high-order is even competitive with P 0 discretisations in problems with heavy advection.

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A new spherical harmonics scheme for multi-dimensional radiation transport I. Static matter configurations

Cited by 92 publications

References 44 publications

General-Relativistic Simulations of Three-Dimensional Core-Collapse Supernovae

General-Relativistic Simulations of Three-Dimensional Core-Collapse Supernovae

Modeling equal and unequal mass binary neutron star mergers using public codes

Angular adaptivity with spherical harmonics for Boltzmann transport

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