skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Some New Verification Test Problems for Multimaterial Diffusion on Meshes that are Non-Aligned with Material Boundaries

Abstract

In this report a number of new verification test problems for multimaterial diffusion will be shown. Using them we will show that homogenization of multimaterial cells in either Arbitrary Lagrangian Eulerian (ALE) or Eulerian simulations can lead to errors in the energy flow at the interfaces. Results will be presented that show that significant improvements and predictive capability can be gained by using either a surrogate supermesh, such as Thin Mesh in FLAG, or the emerging method based on Static Condensation.

Authors:
 [1];  [1];  [1]
  1. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Publication Date:
Research Org.:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org.:
USDOE National Nuclear Security Administration (NNSA)
OSTI Identifier:
1261787
Report Number(s):
LA-UR-16-24696
DOE Contract Number:
AC52-06NA25396
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; Diffusion Verification Multimaterial

Citation Formats

Dawes, Alan Sidney, Malone, Christopher M., and Shashkov, Mikhail Jurievich. Some New Verification Test Problems for Multimaterial Diffusion on Meshes that are Non-Aligned with Material Boundaries. United States: N. p., 2016. Web. doi:10.2172/1261787.
Dawes, Alan Sidney, Malone, Christopher M., & Shashkov, Mikhail Jurievich. Some New Verification Test Problems for Multimaterial Diffusion on Meshes that are Non-Aligned with Material Boundaries. United States. doi:10.2172/1261787.
Dawes, Alan Sidney, Malone, Christopher M., and Shashkov, Mikhail Jurievich. Thu . "Some New Verification Test Problems for Multimaterial Diffusion on Meshes that are Non-Aligned with Material Boundaries". United States. doi:10.2172/1261787. https://www.osti.gov/servlets/purl/1261787.
@article{osti_1261787,
title = {Some New Verification Test Problems for Multimaterial Diffusion on Meshes that are Non-Aligned with Material Boundaries},
author = {Dawes, Alan Sidney and Malone, Christopher M. and Shashkov, Mikhail Jurievich},
abstractNote = {In this report a number of new verification test problems for multimaterial diffusion will be shown. Using them we will show that homogenization of multimaterial cells in either Arbitrary Lagrangian Eulerian (ALE) or Eulerian simulations can lead to errors in the energy flow at the interfaces. Results will be presented that show that significant improvements and predictive capability can be gained by using either a surrogate supermesh, such as Thin Mesh in FLAG, or the emerging method based on Static Condensation.},
doi = {10.2172/1261787},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Thu Jul 07 00:00:00 EDT 2016},
month = {Thu Jul 07 00:00:00 EDT 2016}
}

Technical Report:

Save / Share:
  • In this study, we describe a new algorithm for solving multi-material diffusion problem when material interfaces are not aligned with the mesh. In this case interface reconstruction methods are used to construct approximate representation of interfaces between materials. They produce so-called multi-material cells, in which materials are represented by material polygons that contain only one material. The reconstructed interface is not continuous between cells. Finally, we suggest the new method for solving multi-material diffusion problems on such meshes and compare its performance with known homogenization methods.
  • Days during 1965--68 when significant non-field-aligned diffusion of cosmic ray diurnal anisotropy occurred were studied in detail. It was shown that, whereas a large hour-to-hour and/or day-to-day variability of the interplanetary ecliptic magnetic field direction may favor non-field-aligned diffusion, it is not a necessary condition. Some characteristics of the diurnal anisotropy seem to indicate the possibility that more than one mechanism (sources and/or sinks) operates simultaneously, this situation distorting the usually assumed simple picture of a radially outward convection and field-aligned inward diffusion giving the observed vector along about 18 LT in space. (auth)
  • Surface effects are critical to the accurate simulation of electromagnetics (EM) as current tends to concentrate near material surfaces. Sandia EM applications, which include exploding bridge wires for detonator design, electromagnetic launch of flyer plates for material testing and gun design, lightning blast-through for weapon safety, electromagnetic armor, and magnetic flux compression generators, all require accurate resolution of surface effects. These applications operate in a large deformation regime, where body-fitted meshes are impractical and multimaterial elements are the only feasible option. State-of-the-art methods use various mixture models to approximate the multi-physics of these elements. The empirical nature of these modelsmore » can significantly compromise the accuracy of the simulation in this very important surface region. We propose to substantially improve the predictive capability of electromagnetic simulations by removing the need for empirical mixture models at material surfaces. We do this by developing an eXtended Finite Element Method (XFEM) and an associated Conformal Decomposition Finite Element Method (CDFEM) which satisfy the physically required compatibility conditions at material interfaces. We demonstrate the effectiveness of these methods for diffusion and diffusion-like problems on node, edge and face elements in 2D and 3D. We also present preliminary work on h -hierarchical elements and remap algorithms.« less