Supergranulation-Scale Simulations of Solar Convection Robert Stein, Michigan State University, USA...
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Transcript of Supergranulation-Scale Simulations of Solar Convection Robert Stein, Michigan State University, USA...
Supergranulation-Scale Simulations of Solar Convection
Robert Stein, Michigan State University, USA
Aake Nordlund, Astronomical Observatory, NBIfAFG, Denmark
David Benson, Michigan State University, USA
Computational Domain
• 48Mm x 48Mm x 20Mm
• 5003 grid points
• non-uniform vertical mesh– 12km @ surface
– 70km @ bottom
• uniform horizontal mesh– 100km horizontal
resolution
48 Mm
48 M
m
20 M
m
Computational Domain for the CFD Simulations of Solar Convection
Numerical Method• Spatial differencing
– 6th-order 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
QuickTime™ and aYUV420 codec decompressor
are needed to see this picture.
-- 6.5 hr sequence (out of 50 hrs).-- 6.5 hr sequence (out of 50 hrs).
Velocity in vertical planeVelocity in vertical plane
l to r --> top to bottom
surface, 2, 4, 8, 12, 16 Mm
Continuous scale change: granulates -> supergranules
vertical velocity on horizontal planes
(48 Mm wide)
Upflows at surface come from small area at bottom (left)Downflows at surface converge to supergranule boundaries (right)
Upflows at surface come from small area at bottom (left)Downflows at surface converge to supergranule boundaries (right)
QuickTime™ and aYUV420 codec decompressor
are needed to see this picture.
How to calculate the spectrum?
Average power spectra(correct) or
Average time sequence(incorrect)
Artificial feature,
Noisy
Simulation Data
• Is available– Full data sets ~ 200 Gb per hour solar time– Slices of Vxyz & T at selected depths
~ 2 Gb per hour solar time
• Contact: Bob [email protected]
Solar Physics Post-Doc
Dr. Robert Stein
Michigan State University
• Simulate solar magneto-convection
• Apply to local helioseismology