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Jeffrey Alan Willert

Jeffrey Willert

Phone (505) 667-0178


  • Computational Physics and Applied Mathematics
  • Coupled multi-physics simulations
  • Mathematics
  • Algorithms
  • Partial differential equations
  • Computational Co-Design
  • Monte Carlo methods
  • Jacobi-Free Newton Krylov Methods
  • Applied Math
  • Deterministic Transport
  • Computer and Computational Sciences
  • High performance computing
  • Open MPI development


Numerical analysis and numerical methods including:
  • Solutions to linear systems, Krylov methods
  • Solutions to nonlinear systems, Newton's method, Jacobian-Free Newton-Krylov methods, Anderson Acceleration, Nonlinear Krylov Acceleration
  • Finite difference and finite volume methods
  • Monte Carlo simulation 
  • Numerical Partial Differential Equations

Computation, including:

  • Proficiency in MATLAB, C/C++
  • Open MP, MPI
  • Trilinos Solver Package

Transport Methods, including:

  • Neutron transport fixed-source and k-eigenvalue problems
  • Thermal radiation transport methods
  • Deterministic Sn methods
  • Deterministic acceleration techniques
  • High-order/low-order (HO-LO) methods
  • Moment-Based Acceleration techniques
  • Monte Carlo methods
  • Hybrid Monte Carlo/Deterministic methods
  • Residual Monte Carlo Methods


North Carolina State University

  • Ph.D. completed July 2013
  • Masters completed December 2011

​The College of Wooster

  • B.A. completed May 2009

LANL Positions

Nicholas C. Metropolis Fellowship in Computational and Computer Sciences (Feb. 2014 - Current)

Postdoctoral Fellow (July 2013 - Feb. 2014)

Graduate Research Assistant (Summers 2011 and 2012, Spring 2013)



Willert, Jeffrey, H. Park and William Taitano, Applying Nonlinear Diffusion Acceleration to Fixed-Source Problems with Anisotropic Scattering. Proceedings of ANS RPSD 2014, Knoxville, TN, Sept. 14 - 18, 2014.

Willert, Jeffrey, H. Park and D. A. Knoll, A Comparison of Acceleration Methods for Solving the Neutron Transport k-Eigenvalue Problem. Journal of Computational Physics, 274, pp. 681-694, 2014.

Willert, Jeffrey and H. Park, Using Residual Monte Carlo to Solve the High-Order Problem within Moment-Based Accelerated Thermal Radiative Transfer Equations. Accepted to Journal of Computational Physics. LA-UR-13-29010

Willert, Jeffrey, C.T. Kelley, D.A. Knoll, and H. Park, A Hybrid Deterministic/Monte Carlo Method for Solving the k-Eigenvalue Problem with a Comparison to Analog Monte Carlo Solutions. Accepted to Transport Theory and Statistical Physics.

Willert, Jeffrey, William Taitano, and D.A. Knoll, Leveraging Anderson Acceleration for Improved Convergence of Iterative Solutions to Transport Systems. Journal of Computational Physics, 273, pp. 278-286, 2014.

Zhengzheng Hu, Ralph C. Smith, Jeffrey Willert, C.T. Kelley, High Dimensional Model Representations for the Neutron Transport Equation. Nuclear Science and Engineering, 177, pp. 1-11, 2014.

Willert, Jeffrey, C.T. Kelley, Scalable Hybrid Deterministic/Monte Carlo Neutronics Simulations in Two Space Dimensions. 2013 12th International Symposium on Distributed Computing and Applications to Business, Engineering, & Science, pp. 7 - 10.

Willert, Jeffrey, C.T. Kelley, Efficient Solutions to the NDA-NCA Low-Order Eigenvalue Problem. Proceedings of ANS M&C 2013, Sun Valley, Idaho, May 5 - 9, 2013.

Willert, Jeffrey, C.T. Kelley, D.A. Knoll, H. Park, A Hybrid Approach to the Neutron Transport k-Eigenvalue Problem using NDA-based Algorithms. Proceedings of ANS M&C 2013, Sun Valley, Idaho, May 5 - 9, 2013.

Willert, Jeffrey, C.T. Kelley, Xiojun Chen, Convergence of Newton’s Method for Monte Carlo Functions. Submitted for publication.

Willert. Jeffrey, C.T. Kelley, D.A. Knoll, H. Park, Hybrid Deterministic/Monte Carlo Neutronics. SIAM J. Sci. Comput., 35(5), 62-83, 2013.

Willert, Jeffrey, C.T. Kelley, D.A. Knoll, Han Dong, Mahesh Ravishankar, Paul Sathre, Michael Sullivan, William Taitano, Hybrid Deterministic/Monte Carlo Neutronics using GPU Accelerators, 2012 11th International Symposium on Distributed Computing and Applications to Business, Engineering, & Science, pp. 43 - 47.


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