supergranulation-scale solar convection simulations david benson, michigan state university, usa...
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![Page 1: Supergranulation-Scale Solar Convection Simulations David Benson, Michigan State University, USA Robert Stein, Michigan State University, USA Aake Nordlund,](https://reader036.vdocuments.net/reader036/viewer/2022062308/56649d405503460f94a1aa6c/html5/thumbnails/1.jpg)
Supergranulation-Scale Solar Convection Simulations
David Benson, Michigan State University, USA
Robert Stein, Michigan State University, USA
Aake Nordlund, Astronomical Observatory, NBIfAFG, Denmark
AGU - SPD Conference May, 2005 New Orleans, LA
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Overview
• Purpose
• Computational Methodology (brief)
• Methods for Initializing Simulations
• Preliminary Results: Simulations In-Progress 50Mm x 50Mm x 20Mm (deep) simulations Relaxing thermally and dynamically
• Future Directions
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Significance and Questions1. Second Helium Ionization Zone
• Separate the role of second helium ionization zone from the effect of the increasing scale height with depth
2. Helioseismology• Simulations serve as a tool for analyzing local helioseismic inversion techniques
3. Nature of the Surface Shear Layer
4. Development and Maintenance of the Magnetic Network
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Computational Domain
• 50Mm x 50Mm x 20Mm
• 5003 grid points
• Grid clustering near visible surface
50 Mm
50 M
m
20 M
m
Computational Domain for the CFD Simulations of Solar Convection
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Numerical Method• Spatial differencing
– 6th-order centered f.d.– staggered
• Time advancement– 3rd order Runga-Kutta
• Equation of state– tabular – including ionization– H, He + abundant elements
• Radiative transfer– 3D, LTE– 4 bin opacity distrib. fxn
• Quenching
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Computational Information
• Fortran 90• Parallelized - OpenMP
– single parallel region
• Michigan State University – 64 processor Altix
• NCSA– IBM P690
• NASA Ames– Altix (128 processors)
Objective:
layer MPI on top of the OpenMP
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Initialization Methods24 Mm and 12 Mm Simulations
• 12 Mm simulation (9 Mm deep)• well-relaxed• extended adiabatically to 20 Mm
• Relax dynamics 12 Mm -- 20 Mm deep• Create 24 Mm wide box - and relax the following
1. 12 Mm stretched to 24Mm• generates large scale structure
2. 12 Mm doubled to 24 Mm
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Initialization MethodsConstruction of 50 Mm Initial State
1. Stretch 12 Mm x 20 Mm to 50 Mm• Generates large scale structure• Breaks symmetry
2. Stretch 24 Mm x 20 Mm to 50 Mm• Generates intermediate level structure
3. Quadruple 12 Mm x 20 Mm to 50 Mm• Produces small scale structure
Combine & RelaxCombine & Relax
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Initialization SnapshotsComponents + Composite : Uz at 0.25 Mm
Snapshots of methods + composite (?)
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Initialization SnapshotsComponents + Composite : Uz at 17.3 Mm
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Mean Atmosphere StateTemperature, Density and Pressure
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Mean Atmosphere StateIonization of H and He
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Energy FluctuationNeed for Relaxation
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Future Research Direction
• Relax hydrodynamic simulations (further)
• Implement magnetic field boundary conditions and add Coriolis force terms
• Results will be available to help in answering questions about ...
• Maintenance of magnetic network• f-plane rotation -- Coriolis force• Local helioseismic inversion techniques