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A particle-in-cell method for the simulation of plasmas based on an unconditionally stable field solver

Journal of Computational Physics

Wolf, Eric M.; Causley, Matthew; Christlieb, Andrew; Bettencourt, Matthew T.

We propose a new particle-in-cell (PIC) method for the simulation of plasmas based on a recently developed, unconditionally stable solver for the wave equation. This method is not subject to a CFL restriction, limiting the ratio of the time step size to the spatial step size, typical of explicit methods, while maintaining computational cost and code complexity comparable to such explicit schemes. We describe the implementation in one and two dimensions for both electrostatic and electromagnetic cases, and present the results of several standard test problems, showing good agreement with theory with time step sizes much larger than allowed by typical CFL restrictions.

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TYPE Journal Article YEAR 2016
ScopusOSTIDOI

ASC ATDM Level 2 Milestone #5325: Asynchronous Many-Task Runtime System Analysis and Assessment for Next Generation Platforms

Baker, Gavin M.; Bettencourt, Matthew T.; Bova, S.W.; franko, ken f.; Gamell, Marc G.; Grant, Ryan E.; Hammond, Simon D.; Hollman, David S.; Knight, Samuel K.; Kolla, Hemanth K.; Lin, Paul L.; Olivier, Stephen O.; Sjaardema, Gregory D.; Slattengren, Nicole L.; Teranishi, Keita T.; Wilke, Jeremiah J.; Bennett, Janine C.; Clay, Robert L.; kale, laxkimant k.; Jain, Nikhil J.; Mikida, Eric M.; Aiken, Alex A.; Bauer, Michael B.; Lee, Wonchan L.; Slaughter, Elliott S.; Treichler, Sean T.; Berzins, Martin B.; Harman, Todd H.; humphreys, alan h.; schmidt, john s.; sunderland, dan s.; Mccormick, Pat M.; gutierrez, samuel g.; shulz, martin s.; Gamblin, Todd G.; Bremer, Peer-Timo B.

Abstract not provided.

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TYPE Presentation YEAR 2015
OSTI

ASC ATDM Level 2 Milestone #5325: Asynchronous Many-Task Runtime System Analysis and Assessment for Next Generation Platforms

Baker, Gavin M.; Bettencourt, Matthew T.; Bova, S.W.; franko, ken f.; Gamell, Marc G.; Grant, Ryan E.; Hammond, Simon D.; Hollman, David S.; Knight, Samuel K.; Kolla, Hemanth K.; Lin, Paul L.; Olivier, Stephen O.; Sjaardema, Gregory D.; Slattengren, Nicole L.; Teranishi, Keita T.; Wilke, Jeremiah J.; Bennett, Janine C.; Clay, Robert L.; kale, laxkimant k.; Jain, Nikhil J.; Mikida, Eric M.; Aiken, Alex A.; Bauer, Michael B.; Lee, Wonchan L.; Slaughter, Elliott S.; Treichler, Sean T.; Berzins, Martin B.; Harman, Todd H.; humphreys, alan h.; schmidt, john s.; sunderland, dan s.; Mccormick, Pat M.; gutierrez, samuel g.; shulz, martin s.; Gamblin, Todd G.; Bremer, Peer-Timo B.

This report provides in-depth information and analysis to help create a technical road map for developing next-generation programming models and runtime systems that support Advanced Simulation and Computing (ASC) work- load requirements. The focus herein is on asynchronous many-task (AMT) model and runtime systems, which are of great interest in the context of "Oriascale7 computing, as they hold the promise to address key issues associated with future extreme-scale computer architectures. This report includes a thorough qualitative and quantitative examination of three best-of-class AIM] runtime systems – Charm-++, Legion, and Uintah, all of which are in use as part of the Centers. The studies focus on each of the runtimes' programmability, performance, and mutability. Through the experiments and analysis presented, several overarching Predictive Science Academic Alliance Program II (PSAAP-II) Asc findings emerge. From a performance perspective, AIV runtimes show tremendous potential for addressing extreme- scale challenges. Empirical studies show an AM runtime can mitigate performance heterogeneity inherent to the machine itself and that Message Passing Interface (MP1) and AM11runtimes perform comparably under balanced conditions. From a programmability and mutability perspective however, none of the runtimes in this study are currently ready for use in developing production-ready Sandia ASC applications. The report concludes by recommending a co- design path forward, wherein application, programming model, and runtime system developers work together to define requirements and solutions. Such a requirements-driven co-design approach benefits the community as a whole, with widespread community engagement mitigating risk for both application developers developers. and high-performance computing runtime systein

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TYPE SAND Report YEAR 2015
OSTIDOI

Aleph code electrostatic solver verification

Bettencourt, Matthew T.

Aleph is an electrostatic particle-in-cell code which uses the finite element method to solve for the electric potential and field based on external potentials and discrete charged particles. The field solver in Aleph was verified for two problems and matched the analytic theory for finite elements. The first problem showed the mesh-refinement convergence for a nonlinear field with no particles within the domain. This matched the theoretical convergence rates of second order for the potential field and first order for the electric field. Then the solution for a single particle in an infinite domain was compared to the analytic solution. This also matched the theory of first order convergence in both the potential and electric fields for both problems over a refinement factor of 16. These solutions give confidence that the field solver and charge weighting schemes are implemented correctly. This page intentionally left blank.

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TYPE SAND Report YEAR 2015
OSTIDOI

Towards extreme-scale simulations for low mach fluids with second-generation trilinos

Parallel Processing Letters

Lin, Paul L.; Bettencourt, Matthew T.; Domino, Stefan P.; Fisher, Travis C.; Hoemmen, Mark F.; Hu, Jonathan J.; Phipps, Eric T.; Prokopenko, Andrey V.; Rajamanickam, Sivasankaran R.; Siefert, Christopher S.; Kennon, Stephen

Trilinos is an object-oriented software framework for the solution of large-scale, complex multi-physics engineering and scientific problems. While Trilinos was originally designed for scalable solutions of large problems, the fidelity needed by many simulations is significantly greater than what one could have envisioned two decades ago. When problem sizes exceed a billion elements even scalable applications and solver stacks require a complete revision. The second-generation Trilinos employs C++ templates in order to solve arbitrarily large problems. We present a case study of the integration of Trilinos with a low Mach fluids engineering application (SIERRA low Mach module/Nalu). Through the use of improved algorithms and better software engineering practices, we demonstrate good weak scaling for up to a nine billion element large eddy simulation (LES) problem on unstructured meshes with a 27 billion row matrix on 524,288 cores of an IBM Blue Gene/Q platform.

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TYPE Journal Article YEAR 2014
ScopusOSTIDOI
Results 51–75 of 90
Results 51–75 of 90