On the Development of Parallel Linear Solvers for Simulations of Reactor Thermalhydraulics
NURETH-14 - 2011 September 25-30

Presented at:
2011 September 25-30
Toronto, Canada
Session Title:
D9-1 CASL – Thermalhydraulics Activities in the Consortium for Advanced Simulation of LWRs

Yan Yan (Columbia University)
Steven Antal (RPI)
Brian Edge (RPI)
David Keyes (Columbia University)
Dillon Shaver (RPI)
Igor Bolotnov (RPI)
Michael Podowski (RPI)


The state-of-the-art multiphase fluid dynamics code, NPHASE-CMFD, performs

multiphase flow simulations in complex domains using implicit nonlinear treatment of the

governing equations and in parallel, which is a very challenging environment for the linear

solver. The present work illustrates how the Portable, Extensible Toolkit for Scientific

Computation (PETSc) and scalable Algebraic Multigrid (AMG) preconditioner from Hypre

can be utilized to construct robust and scalable linear solvers for the Newton correction

equation obtained from the discretized system of governing conservation equations in

NPHASE-CMFD. The overall long-tem objective of this work is to extend the

NPHASE-CMFD code into a fully-scalable solver of multiphase flow and heat transfer

problems, applicable to both steady-state and stiff time-dependent phenomena in complete

fuel assemblies of nuclear reactors and, eventually, the entire reactor core (such as the

Virtual Reactor concept envisioned by CASL). This campaign appropriately begins with the

linear algebraic equation solver, which is traditionally a bottleneck to scalability in

PDE-based codes. The computational complexity of the solver is usually superlinear in

problem size, whereas the rest of the code, the “physics” portion, usually has its complexity

linear in the problem size.

Individual Conference-Paper Copies (Electronic Where Available):

  • For CNS members, the first 5 copies per calendar year are free, and additional copies are $10 each.
  • For non-members, the price is $25 for the first Conference-paper copy in a request, and $10 each for additional copies of papers in the same conference and in the same request.
  • Contact the CNS office to order reprints.