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thornado-transport: Anderson- and GPU-accelerated nonlinear solvers for neutrino-matter coupling...

by Ming Tse P Laiu, James A Harris, Ran Chu, Eirik Endeve
Publication Type
Conference Paper
Journal Name
Journal of Physics: Conference Series
Publication Date
Page Numbers
012013 to 012013
Conference Name
International Conference on Numerical Modeling of Space Plasma Flows: Astronum 2019
Conference Location
Paris, France
Conference Sponsor
Conference Date

Algorithms for neutrino-matter coupling in core-collapse supernovae (CCSNe) are investigated in the context of a spectral two-moment model, which is discretized in space with the discontinuous Galerkin method, integrated in time with implicit-explicit (IMEX) methods, and implemented in the toolkit for high-order neutrino-radiation hydrodynamics (thornado). The model considers electron neutrinos and antineutrinos and tabulated opacities from Bruenn (1985), which includes neutrino-electron scattering and pair processes. The nonlinear system arising from implicit time discretization of the equations governing neutrino-matter coupling is iterated to convergence using Anderson-accelerated fixed-point methods, which avoid formation of Jacobians and inversion of dense linear systems. Numerical experiments show that, for a given tolerance, a nested iteration scheme which aims to reduce opacity evaluations can lower the computational cost. Our initial port to GPUs, using both OpenMP and OpenACC, shows an overall speedup of up to ∼ 100× when compared to results using a single CPU core. These results indicate that the algorithms implemented in thornado are well-suited to GPU acceleration.