Skip to main content
U.S. Department of Energy
Office of Scientific and Technical Information

Tensor networks for solving the time-independent Boltzmann neutron transport equation

Journal Article · · Journal of Computational Physics
Tensor network techniques, known for their low-rank approximation ability that breaks the curse of dimensionality, are emerging as a foundation of new mathematical methods for ultra-fast numerical solutions of high-dimensional Partial Differential Equations (PDEs). Here, we present a mixed Tensor Train (TT)/Quantized Tensor Train (QTT) approach for the numerical solution of time-independent Boltzmann Neutron Transport equations (BNTEs) in Cartesian geometry. Discretizing a realistic three-dimensional (3D) BNTE by $(i)$ diamond differencing in space, $(ii)$ multigroup-in-energy, and $(iii)$ discrete ordinates collocation in angle leads to large generalized eigenvalue problems that generally require a matrix-free approach and large computer clusters. Starting from this discretization, we construct a TT representation of the PDE fields and discrete operators, followed by a QTT representation of the TT cores. We then solve the tensorized generalized eigenvalue problem using a fixed-point scheme with tensor network optimization techniques. We validate our approach by applying the method to two examples of 3D neutron transport problems, currently solved by the Los Alamos National Laboratory PARallel TIme-dependent SN (PARTISN) solver.1 We demonstrate that our TT/QTT method, executed on a standard desktop computer, leads to large compression. This allows for the storage of terrabyte-sized neutron angular flux eigenvectors in megabytes. Additionally, we create megabyte-sized full access TT representations of yottabyte-sized transport matrix operators. By leveraging the TT operators and solution methods, we obtain a 7500 times speedup when compared to the PARTISN solution time with an error of less than 10-5.
Research Organization:
Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
Sponsoring Organization:
USDOE Laboratory Directed Research and Development (LDRD) Program; USDOE National Nuclear Security Administration (NNSA)
Grant/Contract Number:
89233218CNA000001
OSTI ID:
2328630
Alternate ID(s):
OSTI ID: 2999962
Report Number(s):
LA-UR--23-29906; 10.1016/j.jcp.2024.112943
Journal Information:
Journal of Computational Physics, Journal Name: Journal of Computational Physics Vol. 507; ISSN 0021-9991
Publisher:
ElsevierCopyright Statement
Country of Publication:
United States
Language:
English

References (33)

Subspace method for multiparameter‐eigenvalue problems based on tensor‐train representations journal March 2022
Some mathematical notes on three-mode factor analysis journal September 1966
O(dlog N)-Quantics Approximation of N-d Tensors in High-Dimensional Numerical Modeling journal April 2011
Numerical Approximation of Poisson Problems in Long Domains journal June 2021
Tensor Networks and Hierarchical Tensors for the Solution of High-Dimensional Partial Differential Equations journal April 2016
Fast and accurate discrete ordinates methods for multidimensional radiative transfer. Part I, basic methods journal June 2001
Analytical benchmark test set for criticality code verification journal January 2003
A Rayleigh quotient method for criticality eigenvalue problems in neutron transport journal April 2020
Computation of extreme eigenvalues in higher dimensions using block tensor train format journal April 2014
Tensor train versus Monte Carlo for the multicomponent Smoluchowski coagulation equation journal July 2016
A low-rank power iteration scheme for neutron transport criticality problems journal December 2022
TT-cross approximation for multidimensional arrays journal January 2010
The tensor-train mimetic finite difference method for three-dimensional Maxwell’s wave propagation equations journal August 2023
Low-rank tensor methods for partial differential equations journal May 2023
A quantum-inspired approach to exploit turbulence structures journal January 2022
Solving the time-independent Schrödinger equation for chains of coupled excitons and phonons using tensor trains journal January 2022
Dynamic Programming journal July 1966
Tensor Rank and the Ill-Posedness of the Best Low-Rank Approximation Problem journal January 2008
Tensor Decompositions and Applications journal August 2009
A Linear Algebraic Development of Diffusion Synthetic Acceleration for Three-Dimensional Transport Equations journal February 1995
Tensor-Train Decomposition journal January 2011
Approximation of $2^d\times2^d$ Matrices Using Tensor Decomposition journal January 2010
The Alternating Linear Scheme for Tensor Optimization in the Tensor Train Format journal January 2012
Low-Rank Explicit QTT Representation of the Laplace Operator and Its Inverse journal January 2012
Solution of Linear Systems and Matrix Inversion in the TT-Format journal January 2012
Multilevel Toeplitz Matrices Generated by Tensor-Structured Vectors and Convolution with Logarithmic Complexity journal January 2013
Alternating Minimal Energy Methods for Linear Systems in Higher Dimensions journal January 2014
A Semi-Lagrangian Vlasov Solver in Tensor Train Format journal January 2015
Why Are Big Data Matrices Approximately Low Rank? journal January 2019
A Multilinear Singular Value Decomposition journal January 2000
Tensor Networks for Dimensionality Reduction and Large-scale Optimization: Part 1 Low-Rank Tensor Decompositions journal January 2016
Tensor Networks for Dimensionality Reduction and Large-scale Optimization: Part 2 Applications and Future Perspectives journal January 2016
Challenging the Curse of Dimensionality in Multidimensional Numerical Integration by Using a Low-Rank Tensor-Train Format journal January 2023

Similar Records

Neutron (and other Particle) Transport at LANL: An Overview [Presentation]
Technical Report · Wed Sep 27 00:00:00 EDT 2023 · OSTI ID:2007319

Tensor Network Space-Time Spectral Collocation Method for Time-Dependent Convection-Diffusion-Reaction Equations
Journal Article · Tue Sep 24 20:00:00 EDT 2024 · Mathematics · OSTI ID:2503531