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Supergranulation-Scale Simulations of Solar Convection Robert Stein, Michigan State University, USA Aake Nordlund, Astronomical Observatory, NBIfAFG, Denmark David Benson, Michigan State University, USA
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Computational Domain 48Mm x 48Mm x 20Mm 500 3 grid points non-uniform vertical mesh –12km @ surface –70km @ bottom uniform horizontal mesh –100km horizontal resolution 48 Mm 20 Mm Computational Domain for the CFD Simulations of Solar Convection
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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
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Mean Atmosphere State Temperature, Density and Pressure
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Mean Atmosphere State Ionization of H and He
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-- 6.5 hr sequence (out of 50 hrs). Velocity in vertical plane
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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)
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Velocity spectrum no features besides granulation
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Upflows at surface come from small area at bottom (left) Downflows at surface converge to supergranule boundaries (right)
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Oscillation modes: k- diagram
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How to calculate the spectrum? Average power spectra (correct) or Average time sequence (incorrect) Artificial feature, Noisy
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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 Stein stein@pa.msu.edu
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Solar Physics Post-Doc Dr. Robert Stein Michigan State University Simulate solar magneto-convection Apply to local helioseismology solarpostdoc@pa.msu.edu
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