The ExaStar project aims to deliver an efficient, versatile, and portable software ecosystem for multi-physics astrophysics simulations run on exascale machines. The code suite is a component-based multi-physics toolkit, built on the capabilities of current simulation codes (in particular Flash-X and Castro), and based on the massively parallel adaptive mesh refinement framework AMReX. It includes modules for hydrodynamics, advanced radiation transport, thermonuclear kinetics, and nuclear microphysics. The code will reach exascale efficiency by building upon current multi- and many-core packages integrated into an orchestration system that uses a combination of configuration tools, code translators, and a domain-specific asynchronous runtime to manage performance across a range of platform architectures. The target science includes multi-physics simulations of astrophysical explosions (such as supernovae and neutron star mergers) to understand the cosmic origin of the elements and the fundamental physics of matter and neutrinos under extreme conditions.
AdamsML (2001) Discontinuous finite element transport solutions in thick diffusive problems. Nuclear Science and Engineering137(3): 298–333.
2.
AlmgrenASBecknerVEBellJB, et al. (2010) CASTRO: a new compressible astrophysical solver. I. Hydrodynamics and self-gravity. The Astrophysical Journal715: 1221–1238.
3.
AndersonDG (1965) Iterative procedures for nonlinear integral equations. Journal of the ACM12(4): 547–560. DOI: 10.1145/321296.321305.
4.
ArgastDSamlandMThielemannF-K, et al. (2004) Neutron star mergers versus core-collapse supernovae as dominant r-process sites in the early galaxy. Astronomy & Astrophysics416: 997–1011.
BalbusSAHawleyJF (1991) A powerful local shear instability in weakly magnetized disks. I - Linear analysis. II - Nonlinear evolution. The Astrophysical Journal376: 214–233.
BorgesRCarmonaMCostaB, et al. (2008) An improved weighted essentially non-oscillatory scheme for hyperbolic conservation laws. Journal of Computational Physics227: 3191–3211.
9.
BrownPNByrneGDHindmarshAC (1989) Vode: a variable-coefficient ode solver. SIAM Journal on Scientific and Statistical Computing10(5): 1038–1051. DOI: 10.1137/0910062.
10.
BruennSW (1985) Stellar core collapse - Numerical model and infall epoch. The Astrophysical Journal Supplement Series58: 771–841.
11.
BruennSWBlondinJMHixWR, et al. (2020) CHIMERA: a massively parallel code for core-collapse supernova simulations. The Astrophysical Journal Supplement Series248(1): 11. DOI: 10.3847/1538-4365/ab7aff.
12.
BurbidgeEMBurbidgeGRFowlerWA, et al. (1957) Synthesis of the elements in stars. Reviews of Modern Physics29: 547–650.
13.
ByrneGDHindmarshAC (1975) A polyalgorithm for the numerical solution of ordinary differential equations. ACM Transactions on Mathematical Software1(1): 71–96. DOI: 10.1145/355626.355636.
14.
CameronAGW (1957) Nuclear reactions in stars and nucleogenesis. PASP69: 201–222
15.
ChuREndeveEHauckCD, et al. (2019a) Realizability-preserving DG-IMEX method for the two-moment model of fermion transport. Journal of Computational Physics389: 62–93. DOI: 10.1016/j.jcp.2019.03.037.
16.
ChuREndeveEHauckCD, et al. (2019b) Thornado-transport: IMEX schemes for two-moment neutrino transport respecting Fermi-Dirac statistics. Journal of Physics: Conference Series1225: 012013. DOI: 10.1088/1742-6596/1225/1/012013.
17.
ColellaPGlazHM (1985) Efficient solution algorithms for the Riemann problem for real gases. Journal of Computational Physics59: 264–289.
18.
CouchSM (2017) The mechanism(s) of core-collapse supernovae. Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences375: 20160271.
19.
CouchSM (2020) Spark: a new solver for self-gravitating compressible magnetohydrodynamics implemented in the FLASH simulation framework. in prep.
20.
CouchSMCarlsonJPajkosM, et al. (2021) Towards performance portability in the spark astrophysical magnetohydrodynamics solver in the {Flash-X} simulation framework. in prep.
21.
DednerAKemmFKrönerD, et al. (2002) Hyperbolic divergence cleaning for the MHD equations. Journal of Computational Physics175: 645–673.
22.
DubeyAAntypasKCalderAC, et al (2013a) Evolution of FLASH, a multi-physics scientific simulation code for high-performance computing. The International Journal of High Performance Computing Applications28(2): 225–237. DOI: 10.1177/1094342013505656.
23.
DubeyAAntypasKCalderA, et al. (2013b) The software development process of FLASH, a multiphysics simulation code. In: SE-CSE, San Francisco, USA, 18 May 2013.
24.
DubeyAAntypasKCoonE, et al. (2016) Software process for multicomponent multiphysics codes. In: CarverJHongNCThiruvathukalG (eds) Software Engineering for Science. London: Taylor & Francis, Chap 1.
25.
DubeyAAntypasKGanapathyM, et al. (2009) Extensible component-based architecture for FLASH, a massively parallel, multiphysics simulation code. Parallel Computing35(10–11): 512–522.
26.
DubeyATzeferacosPLambDQ (2019) The dividends of investing in computational software design: a case study. The International Journal of High Performance Computing Applications33: 322–331. DOI: 10.1177/1094342017747692.
27.
DubeyAWanH (2018) Methodology for building granular testing in multicomponent scientific software. In: SE4Science, held in conjuction with ICSE 2018. Gothenburg, Sweden, 2 June 2018.
28.
DubeyAWeideKLeeD, et al. (2015) Ongoing verification of a multiphysics community code: FLASH. Software: Practice and Experience45(2). DOI: 10.1177/1094342013505656.
29.
DumbserMZanottiOLoubèreR, et al. (2014) A posteriori subcell limiting of the discontinuous Galerkin finite element method for hyperbolic conservation laws. Journal of Computational Physics278: 47–75.
30.
EdwardsHCSunderlandD (2012) Kokkos array performance-portable manycore programming model. In: Proceedings of the 2012 international workshop on programming models and applications for multicores and manycores, pp. 1–10. ACM.
31.
EndeveEBuffaloeJDunhamSJ, et al. (2019) Thornado-hydro: towards discontinuous Galerkin methods for supernova hydrodynamics. Journal of Physics: Conference Series1225: 012014. DOI: 10.1088/1742-6596/1225/1/012014.
32.
FryxellBOlsonKRickerP, et al. (2000) Flash: an adaptive mesh hydrodynamics code for modeling astrophysical thermonuclear flashes. The Astrophysical Journal Supplement Series131: 273–334. DOI: 10.1086/317361.
33.
GardinerTAStoneJM (2005) An unsplit Godunov method for ideal MHD via constrained transport. Journal of Computational Physics205: 509–539.
34.
GearCW (1971) The automatic integration of ordinary differential equations. Communications of the ACM14(3): 176–179. DOI: 10.1145/362566.362571.
35.
GottliebSShuC-W (1998) Total variation diminishing Runge-Kutta schemes. Mathematics of Computation of the American Mathematical Society67: 73–85.
36.
HesthavenJSWarburtonT (2008) Nodal Discontinuous Galerkin Methods: Algorithms, Analysis and Applications. New York, NY: Springer.
HixWRThielemannF-K (1999) Computational methods for nucleosynthesis and nuclear energy generation. Journal of Computational and Applied Mathematics109: 321–351.
JiangG-SWuC-c (1999) A high-order WENO finite difference scheme for the equations of ideal magnetohydrodynamics. Journal of Computational Physics150: 561–594.
41.
KäppelerFGallinoRBisterzoS, et al. (2011) Thesprocess: nuclear physics, stellar models, and observations. Reviews of Modern Physics83: 157–193.
42.
LaiuMEndeveEChuR, et al. (2021) A DG-IMEX method for two-moment neutrino transport: nonlinear solvers for neutrino-matter coupling. Astrophysical Journal Supplement Series253: 52.
43.
LaiuMPHarrisJAChuR, et al. (2020) Thornado-transport: Anderson- and GPU-accelerated nonlinear solvers for neutrino-matter coupling. Journal of Physics: Conference Series1623: 012013. DOI: 10.1088/1742-6596/1623/1/012013.
44.
LarsenEWMorelJE (1989) Asymptotic solutions of numerical transport problems in optically thick, diffusive regimes II. Journal of Computational Physics83: 212–236.
45.
LeeD (2013) A solution accurate, efficient and stable unsplit staggered mesh scheme for three dimensional magnetohydrodynamics. Journal of Computational Physics243: 269–292.
46.
LeeWHRamirez-RuizELópez-CámaraD (2009) Phase transitions and he-synthesis-driven winds in neutrino cooled accretion disks: prospects for late flares in short gamma-ray bursts. The Astrophysical Journal699: L93–L96.
47.
LentzEJMezzacappaAMesserOEB, et al. (2012) On the requirements for realistic modeling of neutrino transport in simulations of core-collapse supernovae. The Astrophysical Journal747: 73.
48.
LevequeR (2002) Finite Volume Methods for Hyperbolic Problems. Cambridge: Cambridge University Press.
49.
LiebendörferMMezzacappaAThielemannF-K, et al. (2001) Probing the gravitational well: no supernova explosion in spherical symmetry with general relativistic Boltzmann neutrino transport. Physical Review D63: 103004.
MesserOEBPapatheodoreT (2018) Exploiting hierarchical parallelism in an astrophysical equation of state using openacc and openmp. Advances in Parallel Computing32: 517–526.
52.
MignoneATzeferacosPBodoG (2010) High-order conservative finite difference GLM-MHD schemes for cell-centered MHD. Journal of Computational Physics229: 5896–5920.
53.
MiyoshiTKusanoK (2005) A multi-state HLL approximate Riemann solver for ideal magnetohydrodynamics. Journal of Computational Physics208: 315–344.
54.
O’NealJWahibMDubeyA, et al. (2020) Domaine-specific Runtime to Orchestrate Computation on Heterogeneous Platforms. Argonne National Laboratory.Technical Report ANL-20/77.
55.
PareschiLRussoG (2005) Implicit-explicit Runge-Kutta schemes and applications to hyperbolic systems with relaxation. Journal of Scientific Computing25: 129–155.
56.
SteinerAWHempelMFischerT (2013) Core-collapse supernova rquations of state based on neutron star observations. The Astrophysical Journal774: 17.
57.
TomovSDongarraJBaboulinM (2010) Towards dense linear algebra for hybrid GPU accelerated manycore systems. Parallel Computing36(5–6): 232–240. DOI: 10.1016/j.parco.2009.12.005.
58.
WalkerHFNiP (2011) Anderson acceleration for fixed-point iterations. SIAM Journal on Numerical Analysis49(4): 1715–1735.
59.
WarrenMSSalmonJK (1993) A parallel hashed oct-tree n-body algorithm. In; Proceedings of the 1993 ACM/IEEE conference on supercomputing, supercomputing ’93. NY, USA, 31 March 1993: ACM, pp. 12–21. DOI: 10.1145/169627.169640.
60.
WasserburgGJBussoMGallinoR (1996) Abundances of actinides and short-lived nonactinides in the interstellar medium: diverse supernova sources for the [ITAL]r[/ITAL]-processes. The Astrophysical Journal466: L109–L113.
61.
WoosleySEWeaverTA (1995) The evolution and explosion of massive stars. II. Explosive hydrodynamics and nucleosynthesis. The Astrophysical Journal Supplement Series101: 181.
62.
ZingaleMKatzMP (2015) On the piecewise parabolic method for compressible flow with stellar equations of state. The Astrophysical Journal Supplement Series216: 31.
