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Computational Astrophysics: Research to Teaching and Beyond Adam Frank University of Rochester Computational Astrophysics: Research to Teaching and Beyond Adam Frank University of Rochester

A Cast of Many Astro. BEAR MHD / Clumpy Flows Sorin Mitran UNC *Andrew A Cast of Many Astro. BEAR MHD / Clumpy Flows Sorin Mitran UNC *Andrew Cunningham (UR, UC Berkeley, LLNL) Alexei Poludnenko (UR, NRL) Kris Yirak (UR Grad Student) Jonathan Carroll (UR Grad Student) Thanks to: NSF, DOE, NASA, UR Laboratory for Laser Energetics

space Simulations: Numerical Experiments with Diff. Eq & PDEs Initial conditions Boundary conditions space space Simulations: Numerical Experiments with Diff. Eq & PDEs Initial conditions Boundary conditions space tim e

3 rd Age of Simulations: n 1 st Age: 1 -D calculations with computers 3 rd Age of Simulations: n 1 st Age: 1 -D calculations with computers – CDC 7600, etc n 2 nd Age: Moderate rez 2 -D calculations – Supercomputers: Cray, etc n 3 rd Age: High rez Multi-D, Multi-physics calc. – Grid Computing, Massively Parallel, Clusters n n We are talking about “Virtual Reality” on a scientific level. Sim. data sets now as “rich” as real data sets – Petabytes/flops 1015 = one quadrillion bytes. n Not just simulation but “Cyberscience” – Integrate IT on all levels of science practice

History: Research Simulation Shocked Clumps Woodward 1976 • Astrophysical environments very heterogeneous. • Winds, History: Research Simulation Shocked Clumps Woodward 1976 • Astrophysical environments very heterogeneous. • Winds, Blastwaves & ISM are all “clumpy” • Interaction of 1 -clump with passing wind is a well studied problem. Critical Parameter tcc: Cloud Crushing Time

Frontiers of Algorithm Development n Adaptive Mesh Refinement – code automatically places grid cells Frontiers of Algorithm Development n Adaptive Mesh Refinement – code automatically places grid cells where needed. n Multi-physics – code simulates many physical processes simultaneously – Magnetic Fields, gravity, radiation transport, chemistry, ionization dynamics.

UR Computational Group: Astro. BEAR Multiyear, Multi grad-student effort Began 2002 Now on 4 UR Computational Group: Astro. BEAR Multiyear, Multi grad-student effort Began 2002 Now on 4 th generation of student

Simulation in Age of Cyber. Science How to maintain 106 line code base across Simulation in Age of Cyber. Science How to maintain 106 line code base across N years M revisions K Student Generations Static documentation doesn’t work. Our solution: Wiki, selfcompiling documentation

Adaptive Mesh Refinement AMR • Different AMR Methods: Grid based regridding Cell based regridding Adaptive Mesh Refinement AMR • Different AMR Methods: Grid based regridding Cell based regridding • University of Rochester Code Astro. BEAR: grid • Hierarchy of Grids • Require Prolongation/Restriction Operators Carry data from one grid level to another • Prolongation (Corse to Fine) • Restriction (Fine to Corse) R. Deiterding

Pre-Planetary Nebula: CRL 618 “Explosion” from dying Solar-type star Mach 10 radiatively cooled bullet Pre-Planetary Nebula: CRL 618 “Explosion” from dying Solar-type star Mach 10 radiatively cooled bullet AMR grid generation in the system

AMR MHD Div B = 0 n n Hydro: Need conservative prolongation/ restriction operators. AMR MHD Div B = 0 n n Hydro: Need conservative prolongation/ restriction operators. MHD: Maintain solenoidal condition. Need divergence free operators on “staggered mesh”. Cunningham et al 2007

Results I MHD Shocked Clump “Standard” Test M = 10 h= nc/nw = 10 Results I MHD Shocked Clump “Standard” Test M = 10 h= nc/nw = 10 b=4

Many Clumps: Radiative MHD Shocks in Heterogeneous Media Cunningham et al 2007 M = Many Clumps: Radiative MHD Shocks in Heterogeneous Media Cunningham et al 2007 M = 10 h= nc/nw = 10 b = 10

How AMR Changes Game: Resolution and Convergence formally defined as approach to known analytic How AMR Changes Game: Resolution and Convergence formally defined as approach to known analytic solution. For complex non-linear problem these rarely exist Define convergence as change relative to highest resolution simulation possible. • For adiabatic shock clump convergence appears at N = 120 cells/Rc

Resolution and Convergence Radiative Clumps Radiative cooling allows post shock flows to collapse – Resolution and Convergence Radiative Clumps Radiative cooling allows post shock flows to collapse – but how far? AMR allows us to run highest resolution radiative clump simulations to date: N = 1500/Rc Highest resolution radiative clump simulations to date: N ~ 1500/R c

Resolution and Convergence Radiative Clumps Radiative cooling allows post shock flows to collapse – Resolution and Convergence Radiative Clumps Radiative cooling allows post shock flows to collapse – but how far? Increases in resolution show qualitatively new behaviors as Dx < lcrit

Resolution and Convergence Radiative Clumps What measures, metrics can we trust at given resolution? Resolution and Convergence Radiative Clumps What measures, metrics can we trust at given resolution? http: //www. pas. roch ester. edu/~yirak/for adam/vorticities. png

Radiative MHD Clumps with Self-consistent Fields Radiative MHD Clumps with Self-consistent Fields

How many MHD-AMR Codes ØNot many ØAstro. BEAR ØFlash ØENZO ØOrion ØAMR VAC ØAthena How many MHD-AMR Codes ØNot many ØAstro. BEAR ØFlash ØENZO ØOrion ØAMR VAC ØAthena

Computation in Teaching My adventure in E-ed-biz 2000 NSF Career Award Astro. Flow – Computation in Teaching My adventure in E-ed-biz 2000 NSF Career Award Astro. Flow – Simulation outreach tool Planetarium asks to buy copy (? !? ) Create Truth-N-Beauty LLC with UR E-education digital media company Produce simulation based modules for: Mc. Graw-Hill, Prentice Hall etc

Second Avenue Software The e-biz goes it alone 2006 Truth-N-Beauty becomes 2 nd Ave Second Avenue Software The e-biz goes it alone 2006 Truth-N-Beauty becomes 2 nd Ave

What we built Celestial Sphere Phases of Moon Seasons Solar System Builder Planetary Atmospheres What we built Celestial Sphere Phases of Moon Seasons Solar System Builder Planetary Atmospheres

Going Beyond Teaching Outreach: Use partners in new media to create interactives for websites. Going Beyond Teaching Outreach: Use partners in new media to create interactives for websites. Discover/Astronomy/Sci. American “Serious Games” – twitch games with a science theme.

Going Beyond Teaching Going Beyond Teaching

Star Formation Star Formation

Conclusions n Computation n Teaching by Simulation – Advanced AMR/multi-physics codes allow new era Conclusions n Computation n Teaching by Simulation – Advanced AMR/multi-physics codes allow new era of simulation – “Weather vs. Climate”: what to do with Petaflops/bytes – New opportunities if done well (graphics, pedagogy) – New opportunities outside of classroom.