1 / 20

Simple Radiative Transfer in Decomposed Domains

This paper discusses a high-order finite difference code for MHD that is memory and cache efficient. It explores the application of this code in MHD turbulence, convection, and accretion discs. It also focuses on the challenges of incorporating radiative transfer in decomposed domains.

ddove
Télécharger la présentation

Simple Radiative Transfer in Decomposed Domains

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Simple Radiative Transfer in Decomposed Domains Tobi Heinemann Åke Nordlund Axel Brandenburg Wolfgang Dobler

  2. The Pencil Code • High order finite difference code for MHD • 6th order in space, 3rd order in time • Memory and cache efficient • Typical applications • MHD turbulence • Convection • Accretion discs • Massive parallelization with MPI (Message Passing Interface)

  3. Radiative Transfer in Decomposed Domains • RT important for optically thin media • Diffusion approximation(s) deficient • RT is a highly non-local problem • Difficult to reconcile with domain decomposition

  4. The Transfer Equation & Parallelization Processors Analytic Solution:

  5. Intrinsic Calculation Ray direction The Transfer Equation & Parallelization Processors Analytic Solution:

  6. Analytic Solution: Communication Ray direction The Transfer Equation & Parallelization Processors

  7. Analytic Solution: Communication Ray direction The Transfer Equation & Parallelization Processors

  8. Analytic Solution: Communication Ray direction The Transfer Equation & Parallelization Processors

  9. Analytic Solution: Communication Ray direction The Transfer Equation & Parallelization Processors

  10. Analytic Solution: Communication Ray direction The Transfer Equation & Parallelization Processors

  11. Analytic Solution: Communication Ray direction The Transfer Equation & Parallelization Processors

  12. Analytic Solution: Communication Ray direction The Transfer Equation & Parallelization Processors

  13. Analytic Solution: Communication Ray direction The Transfer Equation & Parallelization Processors

  14. Analytic Solution: Intrinsic Calculation Ray direction The Transfer Equation & Parallelization Processors

  15. Details about the implementation • Plasma composed of H and He • Only hydrogen ionization • Only H- opacity, calculated analytically No need for look-up tables • Ray directions determined by grid geometry No interpolation is needed

  16. Preliminary Results • 2D model of surface convection • Started from uniform initial state

  17. Preliminary Results • 3D model of sunspot • Started from Nordlund-Stein snapshot • Uniform initial magnetic field added

  18. Preliminary Results • 3D model of sunspot Bottom Surface

  19. Timing results • With 6 rays, and with ionization: 42.7 ms/pt/st • With 2 rays, and with ionization: 37.6 ms/pt/st • No radiation, but with ionization: 19.6 ms/pt/st • No radiation, and no ionization: 8.7 ms/pt/st • Ionization 2.3 times slower! • Radiation either 1.9 or 2.2 times slower.

  20. Conclusions The method • is conceptually simple • is robust (analytic expressions, not limited by table bounds) • has the potential to scale well in parallel environments

More Related