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Title: Symmetry and separability of the neutron diffusion equation

Journal Article · · Journal of Physics Communications
ORCiD logo [1];  [2];  [3];  [1]
  1. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
  2. Univ. of Illinois, Urbana, IL (United States). Dept. of Nuclear, Plasma, and Radiological Engineering
  3. Univ. of Wisconsin, Madison, WI (United States). Dept. of Engineering Physics

Separation of variables is one of the oldest techniques for solving certain classes of partial differential equations (PDEs). As is the case with many other solution techniques for differential equations, separation of variables may be codified within the broader framework of symmetry analysis. Though the separation of variables technique is frequently used in the nuclear engineering context with various equations describing neutron transport, its connection to the symmetries of those equations has not yet been thoroughly established. It is thus the purpose of this work to establish that connection using neutron diffusion as both an initial step toward analysis of more generally applicable equations, and as a connection to previous results in related problems. Using Lie group analysis, it is found that the traditional space-time separable solution of the neutron diffusion equation (featuring a single α-eigenvalue) corresponds to time translation and flux scaling symmetries. Additional solutions of this equation are also constructed using its broader symmetry set.

Research Organization:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Organization:
USDOE
Grant/Contract Number:
AC52-06NA25396
OSTI ID:
1482936
Report Number(s):
LA-UR-18-21934
Journal Information:
Journal of Physics Communications, Vol. 2, Issue 10; ISSN 2399-6528
Publisher:
IOP PublishingCopyright Statement
Country of Publication:
United States
Language:
English

References (6)

Symmetry and Solution of Neutron Transport Equations in Nonhomogeneous Media journal January 2014
Direct functional separation of variables and new exact solutions to axisymmetric unsteady boundary-layer equations journal February 2016
Separation of variables of a generalized porous medium equation with nonlinear source journal November 2002
Geometric Approach to Invariance Groups and Solution of Partial Differential Systems journal April 1971
Symmetry groups and separation of variables of a class of nonlinear diffusion-convection equations journal August 1999
The Differential Form Method for Finding Symmetries journal August 2005

Figures / Tables (2)


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