Engineering topics
Long, Alex Roberts
Publications and source records attributed to Long, Alex Roberts.
Implicit Monte Carlo at LANL-Progress and Challenges
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Monte Carlo Transport Computational Summit-Kickoff
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A preliminary exploration of using mixture density networks for data compression in Monte Carlo codes [Slides]
The thermal radiative transfer equations (TRT) model many important phenomena of interest at LANL. The TRT equations model time-dependent thermal radiation through a medium, i.e., how thermal radiation loses energy by absorption, gains energy via emission processes, and redistributes energy via scattering.
LANL Code Teams' Outbriefs from El Cap Hackathon [Slides]
Abstract not provided.
A novel MC TRT method: vectorizable variance reduction for the energy spectra
Data produced up to now gives us confidence that we will continue to see variance reduction behavior at amenable runtimes as we move this test bed forward. This method has characteristics of event and history based Monte Carlo transport, without the bulky modifications required by event based Monte Carlo while avoiding some overhead.
Jayenne Physics Manual, Revision 1.0 - An Implicit Monte Carlo Code for Thermal Radiative Transfer
This physics manual is intended to document all of the methods used in version 8 of the Jayenne Implicit Monte Carlo solver library. The goal of this manual is to provide a general overview of the basic methods used, and provide a list of references that detail methods that have been implemented in to the Jayenne library.
An Overview of the Implicit Monte Carlo Algorithm [Slides]
Abstract not provided.
LANSCE Pulse
For more than four decades, the United States has relied on the Los Alamos Neutron Science Center (LANSCE) accelerator to deliver high-energy, high-power proton beams in support of national security science. Today the LANSCE facility is a center for materials and nuclear research supporting National Nuclear Security Administration (NNSA) and Department of Energy (DOE) missions.
One-Dimensional Models for Time-Dependent Transport in Solid Cylinders
We present a set of 1-D transport models for solid cylinders of material irradiated with particles on the axial ends. The models are based on 1-D models originally developed for evacuated ducts with reflecting walls. The goal of this work is to show that 1-D models can be used for time-dependent transport in solid cylinders. A future use of this approach will apply these models to the high-energy density physics problem of a Marshak wave propagating down a cylindrical foam or other experiments. The models we present use a Galerkin procedure to project the radial dependence of the 3-D transport equation onto an expansion in terms of polynomials. Results demonstrate that for steady state problems with low scattering ratios, a three-basis function expansion can adequately capture the 3-D solution as computed via Monte Carlo. Smaller number of basis functions did not result in adequate solutions. As the radius of the cylinder increases, the 1-D model is more effective. Results from time dependent problems indicate that the 1-D models move particles too fast down the cylinder at early times, but are accurate on the order of 10 or more mean-free times. Here, our results indicate that 1-D models may be effective in modeling 2-D Marshak waves, but further work is necessary to answer this question.