Publications

63 Results
Skip to search filters

Towards Predictive Plasma Science and Engineering through Revolutionary Multi-Scale Algorithms and Models (Final Report)

Laity, George R.; Robinson, Allen C.; Cuneo, M.E.; Alam, Mary K.; Beckwith, Kristian B.; Bennett, Nichelle L.; Bettencourt, Matthew T.; Bond, Stephen D.; Cochrane, Kyle C.; Criscenti, Louise C.; Cyr, Eric C.; De Zetter, Karen J.; Drake, Richard R.; Evstatiev, Evstati G.; Fierro, Andrew S.; Gardiner, Thomas A.; Glines, Forrest W.; Goeke, Ronald S.; Hamlin, Nathaniel D.; Hooper, Russell H.; Koski, Jason K.; Lane, James M.; Larson, Steven R.; Leung, Kevin L.; McGregor, Duncan A.; Miller, Philip R.; Miller, Sean M.; Ossareh, Susan J.; Phillips, Edward G.; Simpson, Sean S.; Sirajuddin, David S.; Smith, Thomas M.; Swan, Matthew S.; Thompson, Aidan P.; Tranchida, Julien G.; Bortz-Johnson, Asa J.; Welch, Dale R.; Russell, Alex M.; Watson, Eric D.; Rose, David V.; McBride, Ryan D.

This report describes the high-level accomplishments from the Plasma Science and Engineering Grand Challenge LDRD at Sandia National Laboratories. The Laboratory has a need to demonstrate predictive capabilities to model plasma phenomena in order to rapidly accelerate engineering development in several mission areas. The purpose of this Grand Challenge LDRD was to advance the fundamental models, methods, and algorithms along with supporting electrode science foundation to enable a revolutionary shift towards predictive plasma engineering design principles. This project integrated the SNL knowledge base in computer science, plasma physics, materials science, applied mathematics, and relevant application engineering to establish new cross-laboratory collaborations on these topics. As an initial exemplar, this project focused efforts on improving multi-scale modeling capabilities that are utilized to predict the electrical power delivery on large-scale pulsed power accelerators. Specifically, this LDRD was structured into three primary research thrusts that, when integrated, enable complex simulations of these devices: (1) the exploration of multi-scale models describing the desorption of contaminants from pulsed power electrodes, (2) the development of improved algorithms and code technologies to treat the multi-physics phenomena required to predict device performance, and (3) the creation of a rigorous verification and validation infrastructure to evaluate the codes and models across a range of challenge problems. These components were integrated into initial demonstrations of the largest simulations of multi-level vacuum power flow completed to-date, executed on the leading HPC computing machines available in the NNSA complex today. These preliminary studies indicate relevant pulsed power engineering design simulations can now be completed in (of order) several days, a significant improvement over pre-LDRD levels of performance.

More Details
TYPE SAND Report YEAR 2021
OSTIDOI

User Guidelines and Best Practices for CASL VUQ Analysis Using Dakota

Adams, Brian M.; Coleman, Kayla M.; Hooper, Russell H.; Khuwaileh, Bassam A.; Lewis, Allison L.; Smith, Ralph S.; Swiler, Laura P.; Turinsky, Paul J.; Williams, Brian W.

Sandia's Dakota software (available at http://dakota.sandia.gov) supports science and engineering transformation through advanced exploration of simulations. Specifically, it manages and analyzes ensembles of simulations to provide broader and deeper perspective for analysts and decision makers. This enables them to enhance understanding of risk, improve products, and assess simulation credibility. This manual offers Consortium for Advanced Simulation of Light Water Reactors (LWRs) (CASL) partners a guide to conducting Dakota-based VUQ studies for CASL problems. It motivates various classes of Dakota methods and includes examples of their use on representative application problems. On reading, a CASL analyst should understand why and how to apply Dakota to a simulation problem.

More Details
TYPE SAND Report YEAR 2016
OSTIDOI

Aleph Field Solver Challenge Problem Results Summary

Hooper, Russell H.; Moore, Stan G.

Aleph models continuum electrostatic and steady and transient thermal fields using a finite-element method. Much work has gone into expanding the core solver capability to support enriched modeling consisting of multiple interacting fields, special boundary conditions and two-way interfacial coupling with particles modeled using Aleph's complementary particle-in-cell capability. This report provides quantitative evidence for correct implementation of Aleph's field solver via order- of-convergence assessments on a collection of problems of increasing complexity. It is intended to provide Aleph with a pedigree and to establish a basis for confidence in results for more challenging problems important to Sandia's mission that Aleph was specifically designed to address.

More Details
TYPE SAND Report YEAR 2015
OSTIDOI

Boltzmann-Electron Model in Aleph

Hughes, Thomas P.; Hooper, Russell H.

We apply the Boltzmann-electron model in the electrostatic, particle-in-cell, finite- element code Aleph to a plasma sheath. By assuming a Boltzmann energy distribution for the electrons, the model eliminates the need to resolve the electron plasma fre- quency, and avoids the numerical "grid instability" that can cause unphysical heating of electrons. This allows much larger timesteps to be used than with kinetic electrons. Ions are treated with the standard PIC algorithm. The Boltzmann-electron model re- quires solution of a nonlinear Poisson equation, for which we use an iterative Newton solver (NOX) from the Trilinos Project. Results for the spatial variation of density and voltage in the plasma sheath agree well with an analytic model

More Details
TYPE SAND Report YEAR 2014
OSTIDOI

User guidelines and best practices for CASL VUQ analysis using Dakota

Adams, Brian M.; Hooper, Russell H.

Sandia's Dakota software (available at http://dakota.sandia.gov) supports science and engineering transformation through advanced exploration of simulations. Specifically it manages and analyzes ensembles of simulations to provide broader and deeper perspective for analysts and decision makers. This enables them to enhance understanding of risk, improve products, and assess simulation credibility. This manual offers Consortium for Advanced Simulation of Light Water Reactors (LWRs) (CASL) partners a guide to conducting Dakota-based VUQ studies for CASL problems. It motivates various classes of Dakota methods and includes examples of their use on representative application problems. On reading, a CASL analyst should understand why and how to apply Dakota to a simulation problem. This SAND report constitutes the product of CASL milestone L3:VUQ.V&V.P8.01 and is also being released as a CASL unlimited release report with number CASL-U-2014-0038-000.

More Details
TYPE SAND Report YEAR 2014
OSTIDOI

An introduction to LIME 1.0 and its use in coupling codes for multiphysics simulations

Schmidt, Rodney C.; Belcourt, Kenneth N.; Hooper, Russell H.; Pawlowski, Roger P.

LIME is a small software package for creating multiphysics simulation codes. The name was formed as an acronym denoting 'Lightweight Integrating Multiphysics Environment for coupling codes.' LIME is intended to be especially useful when separate computer codes (which may be written in any standard computer language) already exist to solve different parts of a multiphysics problem. LIME provides the key high-level software (written in C++), a well defined approach (with example templates), and interface requirements to enable the assembly of multiple physics codes into a single coupled-multiphysics simulation code. In this report we introduce important software design characteristics of LIME, describe key components of a typical multiphysics application that might be created using LIME, and provide basic examples of its use - including the customized software that must be written by a user. We also describe the types of modifications that may be needed to individual physics codes in order for them to be incorporated into a LIME-based multiphysics application.

More Details
TYPE SAND Report YEAR 2011
OSTIDOI

SNL software manual for the ACS Data Analytics Project

Stearley, Jon S.; Robinson, David G.; Hooper, Russell H.; Stickland, Michael S.; McLendon, William C.; Rodrigues, Arun

In the ACS Data Analytics Project (also known as 'YumYum'), a supercomputer is modeled as a graph of components and dependencies, jobs and faults are simulated, and component fault rates are estimated using the graph structure and job pass/fail outcomes. This report documents the successful completion of all SNL deliverables and tasks, describes the software written by SNL for the project, and presents the data it generates. Readers should understand what the software tools are, how they fit together, and how to use them to reproduce the presented data and additional experiments as desired. The SNL YumYum tools provide the novel simulation and inference capabilities desired by ACS. SNL also developed and implemented a new algorithm, which provides faster estimates, at finer component granularity, on arbitrary directed acyclic graphs.

More Details
TYPE SAND Report YEAR 2011
OSTIDOI

A theory manual for multi-physics code coupling in LIME

Bartlett, Roscoe B.; Belcourt, Kenneth N.; Hooper, Russell H.; Schmidt, Rodney C.

The Lightweight Integrating Multi-physics Environment (LIME) is a software package for creating multi-physics simulation codes. Its primary application space is when computer codes are currently available to solve different parts of a multi-physics problem and now need to be coupled with other such codes. In this report we define a common domain language for discussing multi-physics coupling and describe the basic theory associated with multiphysics coupling algorithms that are to be supported in LIME. We provide an assessment of coupling techniques for both steady-state and time dependent coupled systems. Example couplings are also demonstrated.

More Details
TYPE SAND Report YEAR 2011
OSTIDOI

Foundational development of an advanced nuclear reactor integrated safety code

Schmidt, Rodney C.; Hooper, Russell H.; Humphries, Larry; Lorber, Alfred L.; Spotz, William S.

This report describes the activities and results of a Sandia LDRD project whose objective was to develop and demonstrate foundational aspects of a next-generation nuclear reactor safety code that leverages advanced computational technology. The project scope was directed towards the systems-level modeling and simulation of an advanced, sodium cooled fast reactor, but the approach developed has a more general applicability. The major accomplishments of the LDRD are centered around the following two activities. (1) The development and testing of LIME, a Lightweight Integrating Multi-physics Environment for coupling codes that is designed to enable both 'legacy' and 'new' physics codes to be combined and strongly coupled using advanced nonlinear solution methods. (2) The development and initial demonstration of BRISC, a prototype next-generation nuclear reactor integrated safety code. BRISC leverages LIME to tightly couple the physics models in several different codes (written in a variety of languages) into one integrated package for simulating accident scenarios in a liquid sodium cooled 'burner' nuclear reactor. Other activities and accomplishments of the LDRD include (a) further development, application and demonstration of the 'non-linear elimination' strategy to enable physics codes that do not provide residuals to be incorporated into LIME, (b) significant extensions of the RIO CFD code capabilities, (c) complex 3D solid modeling and meshing of major fast reactor components and regions, and (d) an approach for multi-physics coupling across non-conformal mesh interfaces.

More Details
TYPE SAND Report YEAR 2010
OSTIDOI

Final report on LDRD project : coupling strategies for multi-physics applications

Hopkins, Matthew M.; Pawlowski, Roger P.; Moffat, Harry K.; Carnes, Brian C.; Hooper, Russell H.

Many current and future modeling applications at Sandia including ASC milestones will critically depend on the simultaneous solution of vastly different physical phenomena. Issues due to code coupling are often not addressed, understood, or even recognized. The objectives of the LDRD has been both in theory and in code development. We will show that we have provided a fundamental analysis of coupling, i.e., when strong coupling vs. a successive substitution strategy is needed. We have enabled the implementation of tighter coupling strategies through additions to the NOX and Sierra code suites to make coupling strategies available now. We have leveraged existing functionality to do this. Specifically, we have built into NOX the capability to handle fully coupled simulations from multiple codes, and we have also built into NOX the capability to handle Jacobi Free Newton Krylov simulations that link multiple applications. We show how this capability may be accessed from within the Sierra Framework as well as from outside of Sierra. The critical impact from this LDRD is that we have shown how and have delivered strategies for enabling strong Newton-based coupling while respecting the modularity of existing codes. This will facilitate the use of these codes in a coupled manner to solve multi-physic applications.

More Details
TYPE SAND Report YEAR 2007
OSTIDOI

Enabling fluid-structural strong thermal coupling within a multi-physics environment

Collection of Technical Papers - 44th AIAA Aerospace Sciences Meeting

Hooper, Russell H.; Smith, Thomas M.; Ober, Curtis C.

We demonstrate use of a Jacobian-Free Newton-Krylov solver to enable strong thermal coupling at the interface between a solid body and an external compressible fluid. Our method requires only information typically used in loose coupling based on successive substitution and is implemented within a multi-physics framework. We present results for two external flows over thermally conducting solid bodies obtained using both loose and strong coupling strategies. Performance of the two strategies is compared to elucidate both advantages and caveats associated with strong coupling.

More Details
TYPE Conference YEAR 2006
ScopusOSTI
63 Results
63 Results