Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 12
Book Description
The basic problem addressed in the project was that of accelerating the iterative convergence of Discrete Ordinates (S{sub N}) problems. Important previous work on this problem, much of which was done at LANL, has shown that the Diffusion Synthetic Acceleration (DSA) method can be a very effective acceleration procedure. However, in two-dimensional geometries, only the diamond differenced S{sub N} equations have been efficiently solved using DSA. This is because, for the 2-D diamond-differenced S{sub N} equations, the standard DSA procedure leads to a relatively simple discretized low-order diffusion equation that for many problems can be efficiently solved by a multigrid method. For other discretized versions of the S{sub N} equations, the standard DSA procedure leads to much more complicated discretizations of the low-order diffusion equation that have not been efficiently solved by multigrid (or other) methods. In this project, we have developed a new procedure to obtain discretized diffusion equations for DSA-accelerating the convergence of the S{sub N} equations using certain lumped discontinuous finite element spatial differencing methods. The idea is to use an asymptotic analysis for the derivation of the discretized diffusion equation. This is based on the fact that diffusion theory is an asymptotic limit of transport theory. The asymptotic analysis also shows that the schemes considered in this project are highly accurate for diffusive problems with spatial meshes that are optically thick. Specifically, we apply this DSA procedure to a lumped Linear Discontinuous (LD) scheme for slab geometry and a lumped Bilinear Discontinuous (BLD) scheme for x, y-geometry. Our theoretical and numerical results indicate that these schemes are very accurate and can be solved efficiently using the new method. We describe the concept that underlies the DSA method. We describe the basic asymptotic relationship between transport and diffusion theory.
Numerical Transport Theory ; Final Report
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 12
Book Description
The basic problem addressed in the project was that of accelerating the iterative convergence of Discrete Ordinates (S{sub N}) problems. Important previous work on this problem, much of which was done at LANL, has shown that the Diffusion Synthetic Acceleration (DSA) method can be a very effective acceleration procedure. However, in two-dimensional geometries, only the diamond differenced S{sub N} equations have been efficiently solved using DSA. This is because, for the 2-D diamond-differenced S{sub N} equations, the standard DSA procedure leads to a relatively simple discretized low-order diffusion equation that for many problems can be efficiently solved by a multigrid method. For other discretized versions of the S{sub N} equations, the standard DSA procedure leads to much more complicated discretizations of the low-order diffusion equation that have not been efficiently solved by multigrid (or other) methods. In this project, we have developed a new procedure to obtain discretized diffusion equations for DSA-accelerating the convergence of the S{sub N} equations using certain lumped discontinuous finite element spatial differencing methods. The idea is to use an asymptotic analysis for the derivation of the discretized diffusion equation. This is based on the fact that diffusion theory is an asymptotic limit of transport theory. The asymptotic analysis also shows that the schemes considered in this project are highly accurate for diffusive problems with spatial meshes that are optically thick. Specifically, we apply this DSA procedure to a lumped Linear Discontinuous (LD) scheme for slab geometry and a lumped Bilinear Discontinuous (BLD) scheme for x, y-geometry. Our theoretical and numerical results indicate that these schemes are very accurate and can be solved efficiently using the new method. We describe the concept that underlies the DSA method. We describe the basic asymptotic relationship between transport and diffusion theory.
Publisher:
ISBN:
Category :
Languages : en
Pages : 12
Book Description
The basic problem addressed in the project was that of accelerating the iterative convergence of Discrete Ordinates (S{sub N}) problems. Important previous work on this problem, much of which was done at LANL, has shown that the Diffusion Synthetic Acceleration (DSA) method can be a very effective acceleration procedure. However, in two-dimensional geometries, only the diamond differenced S{sub N} equations have been efficiently solved using DSA. This is because, for the 2-D diamond-differenced S{sub N} equations, the standard DSA procedure leads to a relatively simple discretized low-order diffusion equation that for many problems can be efficiently solved by a multigrid method. For other discretized versions of the S{sub N} equations, the standard DSA procedure leads to much more complicated discretizations of the low-order diffusion equation that have not been efficiently solved by multigrid (or other) methods. In this project, we have developed a new procedure to obtain discretized diffusion equations for DSA-accelerating the convergence of the S{sub N} equations using certain lumped discontinuous finite element spatial differencing methods. The idea is to use an asymptotic analysis for the derivation of the discretized diffusion equation. This is based on the fact that diffusion theory is an asymptotic limit of transport theory. The asymptotic analysis also shows that the schemes considered in this project are highly accurate for diffusive problems with spatial meshes that are optically thick. Specifically, we apply this DSA procedure to a lumped Linear Discontinuous (LD) scheme for slab geometry and a lumped Bilinear Discontinuous (BLD) scheme for x, y-geometry. Our theoretical and numerical results indicate that these schemes are very accurate and can be solved efficiently using the new method. We describe the concept that underlies the DSA method. We describe the basic asymptotic relationship between transport and diffusion theory.
Linear Transport Theory
Author: Gerald C. Pomraning
Publisher:
ISBN:
Category :
Languages : en
Pages : 20
Book Description
Publisher:
ISBN:
Category :
Languages : en
Pages : 20
Book Description
Scientific and Technical Aerospace Reports
Author:
Publisher:
ISBN:
Category : Aeronautics
Languages : en
Pages : 252
Book Description
Publisher:
ISBN:
Category : Aeronautics
Languages : en
Pages : 252
Book Description
Energy Research Abstracts
Author:
Publisher:
ISBN:
Category : Power resources
Languages : en
Pages : 420
Book Description
Publisher:
ISBN:
Category : Power resources
Languages : en
Pages : 420
Book Description
Transport Theory
Author: Richard Bellman
Publisher: American Mathematical Soc.
ISBN: 9780821813201
Category : Mathematics
Languages : en
Pages : 340
Book Description
The industrial and military applications of atomic energy have stimulated much mathematical research in neutron transport theory. The possibility of controlled thermonuclear processes has similarly focussed attention upon plasmas, sometimes called the "fourth state of matter". Independently, many classical aspects of kinetic theory and radiative transfer theory have been studied both because of their basic mathematical interest and of their physical applications to areas such as upper-atmosphere meteorology - introduction.
Publisher: American Mathematical Soc.
ISBN: 9780821813201
Category : Mathematics
Languages : en
Pages : 340
Book Description
The industrial and military applications of atomic energy have stimulated much mathematical research in neutron transport theory. The possibility of controlled thermonuclear processes has similarly focussed attention upon plasmas, sometimes called the "fourth state of matter". Independently, many classical aspects of kinetic theory and radiative transfer theory have been studied both because of their basic mathematical interest and of their physical applications to areas such as upper-atmosphere meteorology - introduction.
Numerical Transport Theory
Author: Paul Nelson
Publisher:
ISBN:
Category :
Languages : en
Pages : 247
Book Description
Publisher:
ISBN:
Category :
Languages : en
Pages : 247
Book Description
Government-wide Index to Federal Research & Development Reports
Author:
Publisher:
ISBN:
Category : Government publications
Languages : en
Pages : 690
Book Description
Publisher:
ISBN:
Category : Government publications
Languages : en
Pages : 690
Book Description
Government Reports Annual Index
Author:
Publisher:
ISBN:
Category : Government publications
Languages : en
Pages : 1106
Book Description
Publisher:
ISBN:
Category : Government publications
Languages : en
Pages : 1106
Book Description
Nuclear Science Abstracts
Author:
Publisher:
ISBN:
Category : Nuclear energy
Languages : en
Pages : 988
Book Description
Publisher:
ISBN:
Category : Nuclear energy
Languages : en
Pages : 988
Book Description
Fusion Energy Update
Author:
Publisher:
ISBN:
Category : Controlled fusion
Languages : en
Pages : 116
Book Description
Publisher:
ISBN:
Category : Controlled fusion
Languages : en
Pages : 116
Book Description