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The NASA HPCC ESS Cooperative Agreement PI: Andrea Malagoli

Turbulent Convection and Dynamos in Stars. The NASA HPCC ESS Cooperative Agreement PI: Andrea Malagoli. Co-Investigators Nic Brummell Fausto Cattaneo Tom Clune Anshu Dubey Bill Gropp Rusty Lusk David Porter Robert Rosner Rick Stevens Juri Toomre Paul Woodward. NASA/GSFC.

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The NASA HPCC ESS Cooperative Agreement PI: Andrea Malagoli

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  1. Turbulent Convection and Dynamos in Stars The NASA HPCC ESS Cooperative Agreement PI: Andrea Malagoli Co-Investigators Nic Brummell Fausto Cattaneo Tom Clune Anshu Dubey Bill Gropp Rusty Lusk David Porter Robert Rosner Rick Stevens Juri Toomre Paul Woodward NASA/GSFC University of Chicago/ANL University of Colorado University of Minnesota

  2. Turbulent Convection and Dynamos in Stars: Performance Milestones [PI: Andrea Malagoli - University of Chicago] All our Scientific Application codes have achieved the 100 GigaFlops performance milestone on the Cray T3E-1200 testbed at NASA/GSFC • MHD-PPM Convection (MHD-PPMC): 195.8 GFlops • The Piecewise Parabolic Method coupled with a parabolic solver. • Solves the equations of compressible (magneto)hydrodynamics • (MHD) with radiative diffusion. • Hybrid PseudoSpectral (HPS): 167.0 GFlops • Uses hybrid finite-difference and pseudospectral spatial derivatives • and a second order time stepping method. • Solves the equations of compressible (magneto)hydrodynamics • (MHD) in a rotating plane. • MHD PseudoSpectral (MPS): 160.0 GFlops • Uses a fully pseudospectral method with Runge-Kutta time stepping. • Solves the equations of incompressible (magneto)hydrodynamics • (MHD) in a triply periodic domain.

  3. The NASA HPCC ESS CAN Turbulent Convection and Dynamos in Stars PI: Andrea Malagoli From Missions Data to Modeling the Sun SOLAR PROBE YOHKOH Granulation and Sunspots The 11-years Cycle Prominences Model of the Sun’s Interior Magnetograms HelioSeismology X-ray images H images Observations data obtained by current NASA missions reveal that complex, highly time dependent phenomena are taking place on the surface of the Sun. These phenomena are related to the vigorous interaction between turbulence, rotation and magnetic fields in the Sun’s Interior. Simulation-based models on NASA’s High Performance Testbeds are used to interpret observations data and to build detailed models of the Sun’s interior. These models play a fundamental role in both the interpretation of current missions data and in driving the design of all future missions SOLAR B TRACE SOHO

  4. Turbulent Convection and Dynamos in Stars: Simulations [PI: Andrea Malagoli - University of Chicago] Convectively driven solar dynamo simulations have been carried out using our Milestones codes on NASA’s T3E testbed. AUTHORS: Fausto Cattaneo and Anshu Dubey - UofC MACHINE: Cray T3E-1200 at NASA/GSFC CODE: MHD PseudoSpectral RESOLUTION: 512x512x97 High resolution simulations are used to study the origin of magnetic fields in the quiet photosphere of the Sun Images from the simulations can be compared with observational images The model suggests that small flux elements are generated locally by dynamo action associated with the granular and supergranular flows Vertical magnetic field Temperature Temperature fluctuations near the upper boundary in a numerical simulation of convectively driven dynamo action. Dark tones correspond to cold (downflowing) material Vertical component of the magnetic field near the upper boundary. Dark and light tones correspond to fields of opposite polarity

  5. Turbulent Convection and Dynamos in Stars: Simulations [PI: Andrea Malagoli - University of Chicago] Coarse grained Original Detail of bipolar magnetic element. The figure shows an area of 200x200 pixels. Same image convoluted with a Gaussian filter with 12 pixels FWHM. Simulation data have higher resolution than observational data. Artificial blurring can be used to compare and interpret observational data AUTHORS: Fausto Cattaneo and Anshu Dubey MACHINE: Cray T3E-1200 at NASA/GSFC CODE: MHD PseudoSpectral RESOLUTION: 512x512x97

  6. Numerical simulations of convectively driven dynamos • Magnetic elements generated by dynamo action display considerable structural complexity • Limited resolution can lead misleading interpretation of true structure of magnetic elements • in terms of oversimplified flux tube models • Numerical simulation can help the development of more realistic models and the design • of high resolution instruments for the detection of small-scale magnetic elements coarse grained original Detail of bipolar magnetic element. The figure shows an area of 200x200 pixels. Same image convoluted with a Gaussian filter with 12 pixels FWHM. Even a modest amount of coarse graining leads to substantial loss of information. Simulations by F. Cattaneo & A. Dubey

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